I wouldnt add wheels too big without lowering the car, you'll make it look like a 4x4.

The 06 six-speed sedan uses the 02-03 TL-S and 01-02 CL-S five spoke, 17" wheels and looks very nice IMO. The tires are sized at 215/50-17.

Here is a good calculator to see what different tire sizes would work and what the affect on the speedometer would be: http://www.1010tires.com/TireSizeCalculator.asp