Are you wanting a car that can/will become your DD? Or just something that you can expect to go to/from events under its own power 99% of the time? Do not take a car to open track events that you really care about and will rely on to get you to work on Monday. You want multiple cars in your stable. The important question is: will this be primarily a toy with something else as a DD, or will this be your primary car with a work horse of some sort in reserve?
2 hours away to do open track is not too far. That's a good distance. Do not base your car decision on a future wheel-to-wheel series. You do not know what you really want yet.
I am also going to assume that you care about learning how to be the best driver you can. If so, you want a car that will not coddle you or bite you. Something that makes you drive it well in order to go fast. Ideally a momentum car. For this reason, I would recommend strongly against an Evo, STi, or Vette. These cars are actually too good. The Evo and STi teach poor driving if you start in them. The AWD covers your mistakes, and power lets you go faster than other beginners even if you make a mistake. This is a bad thing. It means you can not see where you actually need to improve, so you don't. The Vette has the same thing with power, but can also bite if you ham hand it. Consumables on a Z06 are also expensive.
So, I would say E36 M3, Miata, or S2000, RX8, or 350Z as you suggested. (In that order.) Maybe consider a Boxster.
The E36 M3 is just one of the most well rounded cars ever. It will do exactly what you are looking for a car to do. Only trouble is finding one nice enough to satisfy you if you are looking to use this as your DD.
Miata: If this is primarily a toy, get an NB. Beat on it mercilessly, and learn how to be the best driver you can. If it will be your primary DD, get a NC and still whup on it. An NA/NB Miata is hands down the single best car you can start in to learn to be the best driver you can be. Handling is text book. It does exactly what you tell it to. Not necessarily what you want it to, but what you tell it to. It will show your mistakes but not bite unless you get really stupid. When you learn to drive it fast, you will be rewarded tremendously. (I have used a totally DD-able Miata to horribly embarrass $100k Porsche's at an auto-x before.)
S2000: If you can find an AP2 ('04+) in your price range and do not need a back seat, that is what I would get. Low teens will probably get you an AP1 though. They are great. I own one and love it, but am glad I started HPDE in an old Miata. The AP1 is not the best beginner car. The back end is very lively. The reputation for beginners spinning them out is not just Honduh kids who don't know how to drive RWD. If you can reign yourself back a bit, it would still be a good car to learn in and offers much more class and reliability than anything else on the list here.
RX8. Great car like the S2000. Another bad drag car. They have a bad reputation for reliability. My Fiancee has one, and we have not really had any issues. I like my S2000 better. This will be a more beginner-friendly than an S2000 and offer a back seat, but require more money and work in maintenance.
350Z and Mustang: covered better by other people. I will second that I see a lot more Mustangs than Z cars at events. That is probably significant.
Boxster: Price is right now. Not the easiest to work on. Good for a DD that sees toy duty. Seems like you really need to hunt and research and find the right example to minimize the chances of getting one that leaves you with really expensive repairs. I suspect you are also tired of general costs on late-model German cars. PCA is a great organization, and it looks like they do a lot of events at NJ Motorsports Park.