One thing to remember is that you could always upgrade your tickets.
So, if you think you *probably* won't park hop, you could buy tickets without park hopping. Then, while there, if you decide you would like to park hop, you could always hit a Guest Relations and upgrade the tickets. The price would be the same as if you added park hopping when you originally bought them. (Probably best to do that after at least one gate entrance, in case there was a price increase). Only drawback is time spent at Guest Relations, which hopefully won't be long...