1-1/8 front is a very good choice and I imagine 7/8 is fine for the rear from what I heard.
I have been told by others when I was shopping for my front sway bar to never even look at the hollow ones but then I was keeping my /six bars which are tiny. The solid 1 1/8 front held up the car fine and stopped the headers from scrapping on bumps. I suppose if you have the proper torsion bars something smaller or even hollow would be ok.
