I am a frugal traveler, but if time is money then staying at a premium resort for one night which gets you a two day Unlimited Express Pass is worth every penny… as others have suggested. If you do Club Level, you will also save on food.
There are other perks too like early entry which is key for HP. Diagon Alley (where most of the interactive wand stations are) gets really crowded by 9AM and is truly magical between 7-8.
Also, the ability to change after wet rides was a big perk as I described in my trip report (October UOR Trip Report with Tween/Teen Boys)
Have fun.