Ooh, WWOHP is awesome, highly recommended. But you know Universal is currently working on an expansion, right? They're building a Diagon Alley section in the Studios park (WWOHP presently is in the Islands of Adventure park) and there will be a Hogwarts Express train ride linking the two sections. Sounds pretty sweet, you might hold off until that's all open, tentatively sometime next year. Maybe plan your trip for next fall, it should be open by then and crowds and weather are both better in the fall. :)