First, keep in mind that there are only a few of these units at AKL. I think there are 5 or 6 at Jambo, and about double that number at Kidani - so they can go quickly, depending on the time of year. That being said, just some thoughts. The Grand Villas at Kidani are really, really nice, but are actually on 2 floors. The master and living areas are on the first floor. The remaining bedrooms are on the second floor. So if steps are a concern with anyone in your party, it's something to keep in mind. But the rooms are gorgeous, and most have savanna views. The Grand Villas at Jambo are also quite large, but all on the same floor. And since they sort of retro-fitted old existing 'regular' rooms to create the DVC rooms years back, these Grand Villas seem to have some additional space - and they use that space to give you your own billiard table/room in the villa! If you opt for a Jambo GV, our recommendation to you would be to make a special request to NOT be in the unit above the flamingos who live just outside the Jambo swimming pool. Those flamingos are beautiful to watch and enjoy from afar, but they can be quite noisy at times - often at the wrong times!
I hope some of this might help a bit. I'm sure there are others with their experiences and recommendations. If you get the chance to enjoy one of these rooms, do it. We stayed most recently in one at Jambo. The room had an enormous balcony, and ours overlooked the savanna - breakfast on the balcony was a very popular way for our family to start the day!