Thanks for the suggestions so far, keep them coming, I've got some time to decide.
I definitely don't want four doors this time around though--my E36 325i was of course four doors which as much as I loved the car I always wished it was a coupe--it was just a great deal, and here in Japan I don't have much choice but to drive 3-cylinder 4-door tin cans (Daihatsu Mira Custom X FTW!!)
As for location, I don't yet know...I will be either in Minneapolis, San Diego, or New York so that may play a role since the car has to be a DD year-round, as I already have a Camaro as a summer toy in storage. If I'm in MN or NY, the E46 looks attractive, but as does the SLK since it's a retractable hardtop, unlike the Z4--I could get away with driving it in winter if I have to. Unfortunate for any of these cars, but I take care of my stuff and already have a summer toy so it's gotta be a year-round DD.
As for a Camaro, the new ones are pure hotness--but I'm oldskool--300 hp V6 or not, if it ain't a V8, I would never consider it.
More suggestions welcome.