I've stayed countless times in many hotels in KL, but never the SL for some reason. I love the Club at the MO. It quite large with wrap-around views and a nice pool table in the middle. If I need to be in Sentral, I'll stay at the Le Meridien/Hilton complex.
If you go outside KL to Cyberjaya, there is a stunning Marriott. I don't know what the rooms are like as I've only been for lunch a few times, but the building and lobby are quite impressive.
Lastly, I think the most luxurious property in KL is the Palace of the Golden Horses. I really don't know what it is like these days, but back when it opened in the 90's it was pretty amazing. Lots of heads of state stayed there.