Any full size sedan will do 3 across comfortably.
Midsized sedans do it without much hassle, but its still tight.
I've done 3 across in a Honda Accord, Chevy Malibu, and Oldsmobile Achieva.
As far as SUVs, any will do as long as its not a small one. I really like the GMC Envoy XUV, Yukon XL (suburban), and the Honda Pilot/Toyota Highlander.
J-Mom to H (11), L(6), A(12/12/12)