You could also upgrade it to a 10 day non-expiring for about $346 (631 - 285) + tax. This would give you 7 days to use any time. That would be like buying 5 additional (non-expiring) days for $208.
If you wanted a 10 day non-expiring with waterparks, it would be about $407 (692 - 285) + tax. That would give you 7 additional days and 10 waterpark days that can be used any time.