If you want a really cool week-end car you have to get something really unique. Down here in the south there are all sorts of mustangs, camaros, vettes, 350/370Z etc. I am with Zen, go for the Acura NSX or a Lotus Exige. Very cool cars, very unique, total head turners. Out of the box they are fast and fun.
A nissan 350/370Z will always just be what it is unless you really sink a bunch of money into it. Then it is just a modded 350Z. A lotus would be hot. You could even get a nearly new elise for that money.
Just my two cents - buy what you like and have fun.