I surprised my DW with a DL trip this summer. I've never been to DL. My DW went when she was 8 and her great-aunt had a seizure right after entering the park and my DW spent the entire day in the infirmary area below (?) the park. Not very fun for my 8 year old DW. Certainly not very fun for her great-aunt, obviously.
We chose DLH. First, GC rates are too high for our liking. We could probably scrap together the extra cash for GC but we'd rather save that money for an extra meal or
Genie+. Second, and more importantly, DHL looks more authentically Disney (whatever that means). I guess the way I look at Deluxe style hotels is that even though I know I'm overpaying for a hotel, I want to at least have a deluxe feel to the hotel and DHL has that old-style Disney deluxe look to it. I hope my instincts are vindicated when we step foot on property.
DLH is a further walk to both parks as GC has a park entrance to DCA dedicated to its hotel. I think the Monorail slides and pools look nicer and more Disney whimsical feeling at DHL, but that may be just personal preference and nothing more. I like the fact that Trader Sam's and Dole Whips are available onsite at the hotel and GC does not have that option as far as I could tell from my research. My DW and DD are HUGE Dole Whip fans.
My DW, DS and DD are ambulatory adults so we don't have a problem walking through DTD for an extra 5 minutes (more or less) to get to the parks. If you had mobility issues or wanted to have a little one take a quick nap maybe that 5 minutes less of complaining and/or crying (we've all been there before with small children) may be a better option for you.
My DW wanted to be in the Disney bubble. I am more agnostic about that idea but she really wanted the whole DL/DCA experience to be completed with an onsite hotel. I guess if you want that bubble feeling too, then DLH would be a good location based upon all the reports and research I have done.
Lastly, you should be aware and advised that there is a fairly significant construction project going on at DLH. Disney is building a new tower (DVC related?) and that construction project will take quite some time. I haven't heard much about noise issues, but I do fear dust issues. I just know that new construction is a dust maker and I have to believe that dry, Southern California with some moderate to heavy winds can blow dust around which is obnoxious to me.