Princeton's been great so far, except for having to adjust to the new england climate after living in the desert for 21 years. This is arguably the best plasma program in the country, and I'm currently doing theory with one of the top theorists in the field, so I'm content. I had a real difficulty last spring choosing between plasma theory and particle theory (for which my best offer was at Caltech, which is also a very beautiful campus, except for the major gender imbalance), and in the end it was a combination of being solicited heavily by the plasma department here and my philosophical motivations for considering plasma in the first place that made me decide to come here. And I think it was the right decision. As much as I love abstract mathematics, and as much as I believed the only place to truly dive into some hardcore theoretical problems was in particle physics, I've found that there are some seriously stimulating theoretical problems in many different fields, and plasma is no exception. We're basically pioneering the field of nonequilibrium stat mech with a full range of electromagnetic phenomena factored into the mix, so it's pretty intellectually demanding.
So for anyone else who is in a similar situation I was in, namely that you think the only place to get your hardcore math fix is in high energy theory, I encourage you to look into all of the different theoretical disciplines and talk to some professors. But if you really want to do high energy, then go for it, I still have designs to study QFT on the side and become somewhat of an informed bystander.
Good luck you guys, and feel free to ask any other questions about the application process. I'm sure a nontrivial fraction of Princeton's entering graduate class will be coming from the pool of people that frequent this forum.