As for closeness of hotels...
Yes, GCH is close. But unless there's an entrance I'm not seeing (and I've heard there's a secret, locked one in a store somewhere) you either need to be in DCA already, and hopefully near Grizzly, or you're still trekking through 1/3 of DTD, then through endless corridors, to get to the lobby of GCH, where I assume the elevators are.
With DLH, unless you're in Tomorrowland *every* time you are ready to leave, thereby making it simple to catch the monorail, you're still going to have to walk from wherever you are to the monorail. If that makes no sense, you're walking out from the park, through the esplanade, through 2/3 (or more) of DTD to get to DLH.
And with PPH you have to either walk ALL the way through DTD and behind the movie theater (which is a longer walk than to HoJo), or you cut through GCH (probably shorter than HoJo, but a longer walk than, say, Carousel IMO).
Honestly, unless I'm staying at GCH and am already in DCA, or I'm very very close to DL's entrance, the walk to a Harbor hotel is probably going to be closer, or at least even, to even GCH or DLH (unless as I mentioned you're right near the monorail).
So when you're talking about having a close-by room, quite a lot of it depends on where you are and where your room is.