The IS300 is definitely on the short list. I've test driven it and liked it a lot, although it also felt under-powered. The rumor mill for future IS300's is indecisive. In other Lexus cars, they've moved to a 3.3L engine, so it's reasonably to assume something like that for a future IS300. There's also a new Acura TL coming out (spy photos recently appeared on Acura-TSX.com).

I've been trying to convince myself that my daily driver doesn't need to have serious zoom-zoom. It's not going well...