I have stayed at all 3 hotels, and here is what I think. I like all 3 of them for different reasons, but you are right about DLH - it is showing its age a little bit and needs a good tune-up. Up until 2000, I always stayed at DLH.
The PPH is a newer hotel and it looks shinier and fresher on the inside, with pastel colors and a cute beachy/surf theme and Surfer Goofy in the lobby. I have stayed there 4 times (possibly 5 and I blanked out on the other one), and I like it. It is a perfectly fine hotel. The only thing that it lacks is space. It does not have the sprawling property on which to build like DLH has and GCH has. Hence, the cheaper price. The last couple of times I was at DLR, I stayed at PPH. I would have preferred to stay at GCH in December but money did not allow it, so the PPH was perfectly fine. There is absolutely nothing wrong with it and in fact, it is quite adequate, but it just doesn't have anything else to really look at on the property besides the hotel building itself. Definitely stay there if you want a touch of that Disney feeling at the cheapest price. (In my Trip Report, I talk about the PPH stays in October and December of last year - one of them was bad and the other one was good - so check it out if you have time. The link is in my signature below.) It seems kind of far away in the scheme of things, but taking the 'short cut' through the GCH lobby from the PPH is advised!!
As for the GCH, I have stayed there twice. I think it is a great hotel to stay at around the holiday season because it really lends itself to that Christmasy feeling. It is elegantly rustic in theme. It's got dim lighting, dark wood, huge, spacious lobby, a fireplace, a piano player, a lounge and comfy chairs and sofas where you can sip beverages and people-watch - and during the holiday season, there was also a guitar player, a photo session with Santa, an enormous Christmas tree and my favorite - the Christmas carolers who perform in front of the tree every night. I didn't find the actual rooms in the GCH to be that much better than the rooms in the PPH, frankly. The GCH bath products are H20 Spa, whcih are different than the kind that are in DLH and PPH. The beds are kind of tall and firm. The rooms with the view of fireworks and DTD are great because of the view, but they are a looooooonnnng way from the elevators, down seemingly endless corridors, whereas the standard rooms are closer to the elevators.
The bottom line for me is that I lilke the convenience of the GCH due to its close proximity to things, but I prefer the price of the PPH!!! We got so much more accomplished when we stayed at the GCH because we were better rested and my friend did not complain as much about having to re-enter the park after a rest break as she did when we stayed at PPH. Sometimes, at the end of a long, tiring day, saving a few extra steps can make all the difference, and the GCH was so handy because it was right there. The walk back was not daunting. BUT, that said, convenient location aside, I think that most of the appealing features and perks of the GCH can be enjoyed by anyone, and you don't have to actually be a guest at the GCH to take advantage of those things!
It is a BEAUTIFUL hotel and worth a splurge, particularly when you're getting a good discount. Save the PPH for sometime when you can't get a discount. GCH is very elegant and adult; although the pool is fun for kids. It does have things like storytelling by the fire at night for kids, but it just feels more adult-friendly to me. The location is FANTASTIC and very convenient for getting to DTD and the parks.
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. They also offered a washcloth/towel folding class by the housekeeping staff and we did not do this as it was same time as MM and we did not want to miss that. They had a Sephora tour thing and BAB. Also had the walk in CA in the a.m. but I was too worried that I would not be able to keep up and would look like an idiot. 
