I would definitely like to see a rebuilt Vice City using the RAGE engine...All the bright lights, Miami themes, beaches, sunsets...all using the RAGE engine *drools* AND Las Venturas.
I hope Rockstar keeps all the unrealistic human capabilities that made GTA stand out from the crowd; like heads getting chopped off, cartoon-ish violence, and etc. The low quality graphics in III, VC and SA was pretty cool too even though they weren't the best around.