Having gone through almost the exact same decisions, I'll tell you what I know.
Depending on your size, you may feel like Superman driving the Elise but look like a fool getting into and out of your Elise! I tested it, loved the corners, looked like an idiot trying to crawl into and out of the car. If the Elise was 25K, I'd get one, but not for more than that, because it does feel like a kit car and is impossible to imagine as a regular driver. Probably awesome on the track, but never as an everyday ride.
More importantly, think RESALE RESALE RESALE!!! What less than a year ago was fetching $10K over sticker now sits on dealer's lots begging to be purchased. I know of a dealer in South Florida with no less than 32 Elises in stock, new on the floor. He can't give them away at cost, and has started to consider taking a loss on the cars. A car you purchased for $45K the beginning of this year now can't even fetch $35K on ebay anymore. Lotus is the epitome of heritage and design, but really isn't working out in the US market. Be realistic, if you can buy a 2005 car that had a sticker of almost $50K when it rolled off the floor this year for $35K 10 months later, do you really want to be selling one 10 months from now?? Not me!
The Corvette is another story. Personally, I enjoyed the C5 Vette Z06 but never could agree with the ultra lightweight clutch! I just never felt that the GM clutch provided nearly the feedback you could get in an Acura or even a Civic. Lots of power, feels like a rocket, but very poor build quality. The leather in the seats was very often overly worn or ripped in many of the used examples I've found, mostly due to its extremely thin nature. You can also be sure that no-one babied a Z06 around town. It was affordable to just about anyone looking at a moderately priced sports car and many were hammered to the hilt. Good fun to drive for sure, but the tail always seemed a little waggy to me. If you live somewhere with a lot of straight, flat roads, it might be a perfect fit if you find a nice clean example.
As far as the price on the Vette, most of its depreciation should have happened by now, especially with the newer C6 coupe having the same HP as the Z06 of last year. If you decide to go this route, look for a bargain, because they are out there.
NSX is still a mystery to me. Can't decide what I'm willing to pay for one, haven't acquired it yet, but it seems to be my front runner. Also considering 996 Porsche or new Cayman S. Be realistic about what you can afford. Would you rather own a 15 year old 1991 NSX or a 5 year old Corvette? That's a lot to think about, and they'll probably cost the same. Also, if you buy an NSX coupe you may always wish you could have afforded the 1995 or 1997 even to get the T or the extra ponies.
I always think of it this way... What will I love looking at it in my garage? What will I love while I'm writing out the check at my dining room table to make the payments? That's the biggest question of all.
In closing, just be careful you don't go for the Vette and find yourself looking at the 300 others that pass you on a daily basis. If you get the Vette, get it because you love it, not for what others will think. But to me, if you're looking at Elises and NSXs, you'll never be satisfied when someone pulls along side you in the same car, and that will be the Vette.
Good luck to you!
b