On my Grand Prix, I was 215/70-14 front and 225/70-14 rear. Gave it a nice stance, IMHO.
Just went to 205/70-14 front and 205/70-15 Rear because I found a set of Cragar S/S in that configuration with new tires for $350..
Stance is okay, but for some reason, with the mags up front, the wheel wells don't look filled. And the rear 15" are brand new, whereas teh 14's up front are older, and a little crappy.. so I plan on getting two 15x7 5.475's (eg. not unilug) for the front and run 215/70-15 Front, 235/70-15 Rear. (Cooper Cobra's, specifically)
-Gonz