since I am here and have done a few things, I will reply to my own post with helpful info for anyone else.
Batu Caves is neat - about 20-30 minutes from downtown KL. Definitely worth the extra $10 to do the dark cave guided tour.
If you like to see a new city in the making with neat architecture, visit Putra Jaya - about 30 minutes from downtown KL on the way to the international airport. Exquisite buildings, bridges, and even the street lamps are interesting to see.
Garden park, about 10 minutes from downtown has separate parks inside. I visited the bird park and the butterfly park. They cost from $5 to $10 to get in, but very interesting to see.