Len and I were lucky enough to get a (non-private) VIP tour of Universal Studios Florida and Islands of Adventure Friday. We were paired with a Canadian couple who had started their week at Universal with the same tour, went to WDW for a day, and then re booked another VIP tour at Universal because they liked it so much.
Cost is around $300/person for 2 parks/7 hours. They claim 10 attractions with front of the line access. Admission and lunch is separate.
You begin your day at the VIP desk (right by USF guest relations) in air conditioned comfort with morning beverages and pastries.
For some reason, our admission was never scanned when we entered the park - don't know what's up with that.
It was totally worth it right now because of the waits to get into Diagon Alley.
Our longest wait was for ice cream at Florean Fortescue's in Diagon Alley (tasty!)
The thing with the tour is that it's you and whoever else is with you, so there needs to be some consensus about what you want to do and see. The largest group looked to be about 8-10 people (I think they were all in the same family). Ours was probably the smallest with 5. I'd say I saw maybe 40 isn people waiting to start tours (they start at 10 AM and you have access to the guide until 5).
There's are also options to do just one park (not much savings there) and private tours guaranteed with just your group.
I'm considering doing this in cooler weather with my mobility impaired parents just to keep myself sane and not have to do all the herding.
Questions? Ask away.