I've seen Linkin Park twice and both times I haven't actually "seen" them. Both times were at a two festival type things with like 15 other bands and by the time Linkin Park got onstage I would be saving my energy for the final acts so me and a couple of friends would just sit down and sing the songs as loud and as abnoxious as we could. They're just a band you love to hate.(Damn them and their catchy hooks)
Anywho, definately get general floor. If you get seats you'll just be looking at the people jumping around and having fun and then wish you were in there. Most likely if you get general floor you could go anywhere else and try to find empty seats if you don't like the actual floor. Been to many concerts before and that has never been a problem for me. Also it being your first concert definately get into the nitty gritty of things.