Ok well for the birthday you technically have 2 options aside from park admission.... gift card or birthday fast pass.....IMO the gift card is better since u get fast passes anyways. There is a difference between birthday fast passes and regular fast passes. Regular ones you pull and then come back. Birthday ones you get there and you ride with little to no wait. You only get 5 (if i remember correctly) for each person in your party. They apply for any ride but only in 1 park. Now the fast passes would be great if you were to go to MK on the weekend as it would get u on 5 rides really quickly without the long lines but that is up to you. But the best park depends on your and your family's preferences for rides.