Lounging poolside, sipping $18 mini-margaritas under sprawling live oaks, our eyes and wallets opened wide to a life of luxury we didn't really know existed in the city we once knew so well.

Austin's drastically changing skyline was visible from our plush loungers at the small but otherworldly St. Cecilia Hotel. To fully see downtown, though, we had to look over the giant neon sign at the end of the hotel pool, which simply reads "SOUL." It reminded me of Austin's late, great music hero and hippie spirit Doug Sahm, who famously sang, "You just can't live in Texas if you don't have a lot of soul."

In a lot of ways, Austin has sold its soul over the past decade and a half. But at least for one two-night, budget-ignoring, drop-the-kids-at-the-inlaws stayover, we two former Austinites were totally fine with that.

When my wife and I left Austin for Minnesota 12 years ago, the once-sleepy, slacker-minded Texas capital was still a city where you could spend a night out enjoying soul-enriching Tex-Mex food and world-class musicians for the total cost of just one of those petite St. Cecilia margaritas. In hindsight, there was no better place to spend your impoverished 20s living it up than Austin in the '90s.

After an unprecedented 15-year boom, though, the city is bumping up its prices and bursting at the seams. A looming new condo tower pops up just about every year downtown. One oft-quoted population statistic has 150 new residents moving there every day. Traffic jams and infrastructure problems have spiked exponentially.

On the upside, Austin also has welcomed a new tier of restaurants and hotels that can compete with the trendiest hot spots in New York and Los Angeles.

Downtown Austin is booming, bringing both infrastructure problems like traffic jams and a new tier of trendy restaurants, hotels and entertainment.

Five of the city's chefs earned the prestigious James Beard Award nominations in 2013. On the hotel front, both a new W and Hilton high-rise have opened downtown in recent years. The largest is yet to come: A $300 million JW Marriott complex is under construction with 34 stories and 1,012 rooms.

Even the parties are getting bigger and more high-end. The city's new $400 million Formula One racetrack — the kind of auto racing that wealthy Europeans favor — now far outpaces the famous South by Southwest (SXSW) Music Conference in tourism revenue ($500 million this past year). The SXSW music fest isn't even the biggest event for SXSW Inc. anymore: Its tech-centric SXSW Interactive Conference now draws more paying registrants.

Upscale on the south side

For the first time since we moved away, my native Texan wife and I experienced Austin the way today's business travelers and wealthy new residents get to enjoy it.

We found "a deal" at the St. Cecilia in early April, giving us access to what seemed like a secret society of Austin's upper-crust hangers-on for a mere $295 per night. We took that as a cue to hit some of the city's newer, costlier restaurants and trendy areas instead of sticking with the old, mostly inexpensive standbys we usually favor. (We still love you, Curra's and El Azteca.)

The St. Cecilia itself is as much an attraction as it is a hotel. Laid out around a 125-year-old white Victorian house and scenic estate in South Austin, the property is just a block off one of the city's liveliest strips, South Congress Avenue — "SoCo" if you're a real estate agent or new Austin transplant trying too hard.

Actually a cluster of six bungalows, five suites and three studios, the St. Cecilia boasts a turntable in each of the spacious rooms and large vinyl library in the lobby, plus vintage but comfortable furniture and artful design. The hotel was converted in 2008 by Liz Lambert, an Austin visionary.

Lambert's nearby 40-room, desert-styled San Jose Hotel — a cheaper option than the St. Cecilia — helped reshape South Congress from a once-derelict strip to a shopping and dining destination visited by every hipster tourist nowadays. And for good reason.

Both properties are walking distance from the Continental Club, a roots-rock and vintage-country haven that's one of the few relevant music venues of yesteryear not closed or bulldozed by "development."

Farther down the avenue lies the popular taco palace Guero's, the more upscale Tex-Mex eatery South Congress Cafe and a trove of clothing, art and vintage shops, including the coolly eclectic antique mini-mall Uncommon Objects.

South Congress was only the first of the new era of trendy districts quickly evolving in Austin. Just a few blocks west lies South First Street, which boasts several chic new restaurants, including two new French-flavored joints. (Hey, France was also one of the six flags of Texas.)

The elegant yet cozy Lenoir boasts a good-value prix fixe menu and a "wine garden" instead of a beer garden.

On a previous trip, we hit Elizabeth Street Cafe, a French-Vietnamese-inspired eatery that somehow still felt uniquely Austin.

The trendiest of the new shopping and nightlife districts, though, is also the unlikeliest: East Austin, just under Interstate 35 from downtown. Only 20 years ago, crack houses were as numerous in that part of the city as bohemian-chic boutique stores are today.

East Austin is where folks start lining up at 9 a.m. and wait two-plus hours to get some of the limited quantities of brisket and ribs at Franklin Barbecue (the nearby La Barbecue is an excellent backup for those turned away). It's also the part of town that hosts arguably the hottest new high-end eatery — which proved highly disappointing to us.

Some high-end lows

I've never laughed so hard at the sight of a to-go box than when I saw one at Qui, an uber-trendy Asian-fusion restaurant run by "Top Chef" TV contest winner and Beard Award recipient Paul Qui. His open-air, bamboo-lined space is gorgeous, but the serving sizes were so small you could fit most menu items inside a matchbox, and the high-concept food generally had a texture best described as snotty.

We had a much better experience on a previous trip eating at another edgy, Beard Award-winning chef's modern Asian place, Uchiko.

After Qui, we crossed back to the downtown side of I-35 to stroll yet another hopping strip that surfaced in the past four years, Rainey Street.

Set entirely in historic houses near the Austin Convention Center, Rainey Street's lineup of bars and restaurants now competes with the better-known but locally ho-hummed Sixth Street entertainment district for collegiate nightlife dollars. Even us less-rowdy old folks found the giant patio at the Banger's Sausage House & Beer Garden hard to argue with on a not-too-warm Austin night.

An alternative to — and perhaps contributor to — its overstuffed roads, Austin is still a relatively compact city. Its walkability is still one of its best assets, the reason the SXSW fests work so well.

The next day, we walked from South Congress up to the West Second Street district, another shopping and dining area centered around the W Hotel and the best instance of Old Austin getting a posh upgrade: the $40 million Moody Theater, where the famed PBS music show "Austin City Limits" moved in 2011 after spending 36 seasons in a cramped old studio on the University of Texas campus.

Used for nontelevised concerts, too, the Moody instantly became one of the best midsize concert venues in the country. It's usually packed with concerts or tapings during the two early-October weekends of the TV series' hugely successful offshoot, the Austin City Limits Music Fest.

Another part of the city where things have picked up more for the upper set is the once-hippie-flavored Clarksville area on the western edge of downtown. That's where we discovered our two favorite new restaurants, the Josephine House and Clark's Oyster Bar.

Housed next to Jeffrey's — one of Austin's longest-serving fine-dining restaurants — the Josephine House is another gorgeously refurbished old house with fancy charcuterie and cheese trays and simple but divine farmhouse dishes. Clark's defies Austin's long lack of decent seafood with oysters from British Columbia and a lobster roll from heaven.

It was during our dinner at Clark's when we had something of a defining moment. Someone at the patio table next to us had their dog with them, an occurrence we wouldn't have blinked at in the more hippie-ish days of Old Austin — but Fido sure seemed out of place in this posh new hot spot (with raw seafood and all).

Once we quietly moved inside for dinner, our newfound uppity ways screamed at us in shame. So we went for $5 margaritas afterward and took in the dazed-and-infused organ rock trio Dupree at the Continental Club, fighting to at least save our own souls.

Chris Riemenschneider • 612-673-4658