Traditionally, it's been better to book room only and wait for codes, but depending on your circumstances, this year the Fairytale Package seems to be offering the best deal, particularly if you need tickets. This deal means you pay for four days at rack rate and get tickets and lodging for up to 7 days (if you can stay 7 days you're getting 3 free). This is a great deal- almost 43% off rack rate in some cases.
Your other options are to buy an Annual Pass for one member of your group, then buy either a UPH( great if you want flexibility, and will visit the waterparks and PI) or the park hoppers. You'll have to crunch the numbers- depending on the number in your party, the resort you want to stay at, the time of year you're going, you'll see which offers the best.
If you post your info here- number of people, time of year, resort, what you like to do, length of stay, then I have no doubt some of the experts on the boards here will give you some options.
In answer to your original question- we stayed room-only last year and got our UPH's at check-in.