Good for you. I'm too lazy to do the summer school thing; I wish I had that drive, but I need my down time more than a lot of people.
I think the following certification organizations are all good: NSCA, NASM, ACSM, and ISSA. From the research I've done, all of them seem to require that you actually learn something and seem like quality certifications. Of course, ACE is accepted everywhere, but any douchebag dumbshit who's read a few FLEX magazines could pass that. You need a 4 year degree to take the ACSM PT certification, and a 4 year degree for the NSCA-CSCS too. The NSCA-CPT (The one I took) is up for grabs without the degree though.