The website will automatically select 6 day tickets if you choose a 5 night reservation. If you would have opened up the "Theme Park Tickets" section, you could have selected a different number of days for your theme park tickets and it even shows the price difference to go down or up. You'll save about $20 a ticket to downgrade one day. (Go back and pretend to make a new reservation and you'll see what I mean.) You can call and ask to modify your reservation. I'm really not sure if they'll penalize you for doing it in the 45 day window if you've already paid, but it's worth a shot. In the alternative, if you're arriving early enough in the day to get to one of the parks if even just for fireworks, it might be worth it to start your trip off with a bang (so to speak).