Edit: Thanks for the clarification Robert.
The perks for the hotel guests are all part of the licensing/lease deal between Universal and Loews, I've been told. Universal selected Loews to develop and run those hotels as Universal's not in the hotel business. But UO works with Loews in the hotels' promotion and integration with the rest of the resort. So they're not exactly like some random hotel that just happens to be in the area.
As for what Blackstone will do now, well, it's cashed out and that money goes into the till for its managers to reinvest in other acquisitions, in companies that it currently holds, or in payments to investors. Remember, Blackstone owns a ton of other stuff, not just Merlin and SeaWorld (which are operated independently of each other, BTW.)