Both pool areas are fun for kids. I prefer the DLH because it has more landscaping and there is also a separate (as in completely separate) quiet pool area which we really enjoyed. There is a laundry room right there by the quiet pool as well as a sand area with a volleyball net which my kids thought was very neat. And they have the remote control jungle cruise boats and arcade near the pool area. Again, all things my kids loved (no arcade at the GCH if you have a teenage son as I do that is not a good thing!). The Neverland Pool at the DLH also has more shade, the GCH pool area is a bunch of concrete and not much else in the way of landscaping. Both pools have food available, Whitewater Snacks is a bit more upscale with more variety than
Crocs Bits n Bites, but both are good. There is also a coffee shop right near the DLH pool that has muffins and pastries to snack on. The GCH pool has a nice view of DCA and the Sun Wheel which really makes you feel very connected to the parks. I think both pools are very nice and about equal in pros and cons. I just like the palm trees at the DLH pool. Since I live in Colorado, the pine trees and mountain theme of the GCH don't feel that exoctic to me! And I much prefer the lighter, brighter, larger rooms of the DLH and the fact that if you don't get a daybed you get a rollaway as opposed to the GCH where you might end up with a sleeping bag if you don't get a bunkbed or daybed room. The GCH does have balconies in most rooms which is a huge plus.
I don't think you can go wrong either way. I am just very partial to the DLH and in seven stays have never been disappointed. And for once in my life, I actually prefer the cheaper option!