I am particularly fond of cotton/sweatpant type, capri-length, slightly bootcut/flared pants with pockets.
LOL - I know, I'm specific! But they are really what works best for me, at ALL weight ranges (from my highest to now, this is what I have worn). I hate shorts, so I never wear them, but the capris keep you nice and cool.
http://www.amazon.com/Reebok-Womens-...601913&sr=1-15
I like having the pocket for an mp3 player, too.
As for tops, I like regular cute t-shirts. Old Navy usually has a bunch of cute ones in the clearance section, so I've never spent more than 5 dollars for a workout t-shirt.