We are going to UO next Wednesday-Friday. I bought 3-day park-to-park tickets. I realized that it would have only been $135 more (total) for our tickets to be "Power Passes". Can we upgrade the tickets once there, after we see how much we like it or do I need to make the decision before we go (before we use the tickets I bought)? It is not a lot of $$ to get a year's access but, given we're from Massachusetts, we wouldn't go back unless we really like it so I'd rather not spend the extra unless we know for sure we want to go back.