I recently bought a Good Cook brand sheet cake pan, not realizing that it was nonstick. I'm was wondering what kind of nonstick coating it had, since the only coatings I know of are ceramic and teflon, and I usually expect to see a darker color on teflon pans.     What kind of nonstick coating does this pan have? 
You can either add a lot of vinegar (to get above the problem area) -- or you can try to displace the vinegar so you don't need as much.  Find a smaller pot and fill it with water and set it in the center of the pot to clean, and then pour vinegar between the two pots (or pot & item).  Although I said 'fill it with water', you only really need a little bit more than what you need to keep it from floating once the vinegar is in there.  If you don't have a suitable pot, look for anything else that you can use that is heat safe, non-reactive, won't float (in that amount of vinegar), and will fit inside the pot.  And if you're using an anodized aluminum pot, check the bottom for scratches -- odds are they'll oxidize over time (a white powder forms), and if you have a lot of scratching, you might not want to give it an acid bath. 