Scratching the surface

The title may be "JFK & LBJ: A Time for Greatness," but this fast-paced documentary focuses primarily on Lyndon Johnson's passion behind the 1964 Civil Rights Act — and how he used John Kennedy's death to get it. It's a fine introduction for those new to that time in history, but anything involving a bigger-than-life figure like Johnson deserves a running time longer than one hour. 8 p.m. TPT, Ch. 2

Sister act

Nikki Alexander, who has carved out a career as a reality TV star, brings her family into the business through "It Takes a Sister," a new series about bickering but fairly likable siblings trying not to rip one another's hair out in Knoxville, Tenn. 8 p.m. Oxygen

The big bounce

The ups and downs of being one of the first openly gay athletes in the U.S. is examined in "Back On Board: Greg Louganis," a new documentary that looks at the life of a public figure who has largely disappeared since his Olympic diving triumphs in 1976, 1984 and 1988. 9 p.m. HBO

Neal Justin