check out this site, they've got several options for wheels for G8's, either same size or staggered. tires are a bit on the pricy side though.
http://www.bigwheels.net/index.php

thanks, They don't offer a staggered set, but, the driv wheels look pretty good and definetly good price.

I suppose I shoulda mentioned that they have staggered widths, but nothing with staggered diameters

Has anyone ever had any experience with bigwheels.net? They seem to have a nice selection of high quality, nice looking wheels (a decent amount of fugly ones as well though)... Just wondering if they are legit or not and if they actually measured for fitment on a G8?

Wheels and more wheels:

http://wheelstudio.com/catalog/vehicles.php?vehicle_make=Pontiac&vehicle_model=G8%20>%202008->

For all of you guys who are ready to swap out your 19" wheels, I'll give $100 per wheel for the first four, after you burn off all the rubber from your summer only's. My #287 has 18"s, which are fine, but I would like a set of 19"s for intermittent use.

Wheels and more wheels:

http://wheelstudio.com/catalog/vehicles.php?vehicle_make=Pontiac&vehicle_model=G8%20>%202008->

Do all those fit the G8? .... shoot that's great if they do ...but i kinda don't believe it (seems like a list of everything they sell)

All the wheels are 5x120, the offsets they have listed for each wheel are what will fit the G8.