H.K.
What a fun Mom you are!
We haven't done Universal Studioes in a while, but when our boys turn 10 they take a special one-on-one trip to Six Flags Magic Mountain with Dad.
We find Six Flags to be very "boy friendly" with all the high adreneline roller coasters.
Six Flags also has great discount coupons (usually 2 for 1) at Burger King or Fry's.
You can always cut costs where ever you go by taking in a backpack of treats and water bottles. My guys left the park at lunch time and went to a nearby fast food resturant.
When booking a hotel always ask for a manager and ask if that is the best rate they can offer, more than once I have received an employee rate using this tactic.
Pack your food for the drive (so you are not dropping $20 at a burger joint) and this way you'll have snacks in the hotel room as well.
If possible bring a game system to plug into the hotel t.v. (so you aren't tempted to pay for the games they offer). Bring some new pool toys to make swimming in the hotel pool much more fun!
Have an awesome time wherever you go!