It is actually a good choice to stay for one night in the afternoon and go back to the city the next day. There are many things to play there.
If you live in KLCC, you can go to Genting, the Central Railway Station, or to the other direction, the subway terminal. There is genting bus. Unless you live in Chinatown (Cichang Street), you can take Genting bus at Pudulaya, Du Fu Station.
KL SENTRAL has direct buses to LCCT, namely Red Sky Bus and Yellow Star Shuttle Bus, which leave at 3:30 at the earliest and run every half hour.