Bullwings

I don't know if it's been mentioned yet in this thread as I only read the first post and briefly scanned through the other posts. BUT...

Two purpose built cars is better than 1 all around car to try to do everything. I say pick up a DD for under $25K and keep the S2K. S2K can be the fun weekend car for everything. Plus, if you really want to go to VIR a few times a year, it's much better to have a second car. Stuff can ALWAYS happen at the track, even if you're driving at 6/10ths and completely under control. All it takes is someone dumping oil in the wrong spot and your car is gone. It'll be much easier to part with a ~$18K fully paid S2k than a $40K Cayman S or E90 M3 that you're still making payments on...

I say pick up an Si for a DD like Chris did (sold his E90 M3) and keep the S2K. Or a GTI

BRZ/FRS - stay away until they sort out the problems with direct injectors failing, causing the motor to run lean and seize up

I like a lot of cars on your list, but I wouldn't give up my S for any of them and keep them as my only car. And for me, some of those cars are way too expensive for me to track both from a consumables stand point and the possibility of getting into a wreck - I used to have a GRB STI, and after 3 track days and constantly seeing crashed cars, I couldn't stomach it - I got an S2K at half the price (on top of all the other pluses associated with the S2K).

DHonovich

I vote an evox...
I have an s2000 for track duties and drive my evox as a DD but if I had to only choose one car it would be the evox because it is a much better DD.

Bizhan

For around $35k, you might consider an 08-09 ISF. Lexus reliability, nice styling, gobs of power, fun to drive, and rear seats to boot.

EVAN&MONICA

Probably the best and most relevant response so far in this thread

Sebring AP1

S54 z3mcoupe or a 964/993 and start messing with it how I want.

Those are about the only two substitutes I could "live" with if the S2000 didn't exist.

Vitt

If you're going to wait until the spring you should test drive the new 228i Sport (replacing the 1 series). It will be lighter than the 328, and that engine should give it plenty of grunt and should help the handling since it is lighter on the nose than the 6 cyl turbo. The only drawback is that you can't get a factory installed LSD on the 4 cyl., but I'm sure Quaife will have one in short time. It is 'expected' that the steering will have improved over the current EPS on the 3 series.

I also second the other opinions on considering the 3 series or the new Chevy SS. It's supposed to be a whole lot of car for the $$.

Chris S

I've had several of these cars (S2000 x 3, E90 M3, Cayman S, and now Civic Si sedan), and have experience all the others on your list aside from the Audi. They're all good to great cars, but I'd start by ruling out the 370, Cayman S, and BRZ since they don't meet your criteria of a real back seat. The E90 M3 was probably the best car I've ever owned. It was comfortable, fast, and practical. It was also very thirsty and I could foresee that it was going to get more expensive to maintain. I sold it for $36k, pocketed the proceeds, then financed my new Ciivic Si for 60 months @ 0.9% (Honda promo still running). Got one w/ Nav for only $21,235, which is a steal IMO, so payments w/ minimal down are only $350.

It's getting near double the gas mileage of the M3 while still being plenty fun...in fact, it's even more fun in some situations, b/c you can wind it through the gears w/o hitting "go to jail" speeds as easily as the M3, which really needs to stretch its legs to feel fast. The Si also has better electronics, w/ bluetooth streaming, Pandora app, XM, backup camera, etc. (though the stereo doesn't sound as good as my old M3's premium system). Another nice thing about it is that it's the only sporty sedan or hatch I'm aware of that weighs under 3,000 lbs., and it feels light on its feet. I installed a Progress 24mm adj. rear swaybar, which really livened up the handling. The 2.4L engine has plenty of power for my needs, and you don't have to wind it out to access it. We've been getting 28-30 mpg mixed driving, and 34-35 on the highway. I have to admit I would have preferred the BRZ had it been more family friendly and if I wasn't concerned about engine reliability.

Others on your list:
STI hatch: I like them, and considered one before getting the M3 instead. I like them, but not wild about the interior and gas mileage.

Hyundai Genesis Coupe - they're good values, and handle decent. Seems like something funky is going on w/ the shifter/clutch/throttle during shifts. As sacrilegious as it may sound, I'd def. try and consider the 8 sp. auto before making a decision on one of these. 10 yr. powertrain warranty is nice if you can avoid modding it.

kolyan2k

For $30k you can get CPO 335 fully loaded
For $40k you might get CPO Cayman

EastS2k

370z beats out all the competition;

-reliability (no turbos to go wrong long term)
- you are taking a loan out, imagine a current day 350z, you can expect the 370 to have a similar overall presence at the end of your loan, meaning it will still look good and look fairly modern, depending on mileage and condition you have a good chance of recouping a good % of your money...
-not underpowered, meaning you could just lower it, slap a good sounding exhaust on it and have a reliable/quick dailydriver, oh you can get a brand new Base/sport for 31k
-I hated it they way it looked when it came out, but it has grown on me.
(I might get bashed for the next comment)
-the 370 is a perfect blend of s2000 and 5.0 mustang, taking a bit from both and settling in the middle.
-Intake/exhaust/tune puts it around 360hp, just right for a 3200lb car.

cons
-You either like the looks or you hate it
-The v6 drinks as much fuel as a v8 in the mustang.
-? no backseat
-not easy to extract power from the vq37 (highest i've seen on forums from bolt on and a tune was 350whp, average is around 330whp)

Marioshi

Dang, you beat me to it. I think the Golf R is a little expensive for what it is but it certainly meets all the OPs requirements.