Rims I'd like to upgrade to...

BBS RS Rims are awesome

Driveby video

But they're expensive :(

BBS LMs
Again they're expensive but they look great!
BBS Rims seem to be the go
But I wouldn't mind Team Dynamics, they're lightweight and cheap.
I'd probably get the Pro Comp 1
I've upgraded my engine, now I'm going to focus on better handling, ie. Springs, Shocks, Swaybars, Rubber, steering rack etc.