...hmm
Well if it was my honeymoon I'd want to rent a really nice villa with its own private pool and hot tub... especially in July since the weather will be hot. I'd want to swim sans children in the afternoons. To me there's nothing romantic than my own pool.
Depends upon what type of resort activities your brother would be interested in... there are a lot of wonderful villa based resorts in the Walt Disney World area - Ginn Reunion, Windsor Hills, Highland Reserve, Indian Creek and Emerald Island are all nice places. Just look for a home with high end furnishings.
But, if I had to stay onsite, then I'd get either one of the suites at the Grand Floridian, or a 1 bedroom condo at Old Key West. You would have a really nice ginormous jacuzzi at OKW, along with a large walk-in shower.
If they decide to head to Universal, then by all means stay at one of the Universal hotels those days. I'd suggest Portofino Bay at Universal.
I hope they have lots of fun planning it!
Lisa