Other things to consider:
Grand Californian is in a serious need for a refurbishment. We just stayed in August and we had 2 broken toilets, a loud gurgling sink and no wifi for 6 days. Not to mention stained and discolored hallway rugs and an odd mildew smell outside our room. Everything seems like it needs to be refreshed, ya know? Just kinda old, but not in a fun vintage way but in a early 2000s way. Also, like 2 electrical outlets for the whole room.
Room size. GCH is almost the same room size and layout as Wilderness Lodge or Animal Kingdom Lodge. DLH is more akin to I would say the Polynesian. Maybe a hair smaller, but that same size where you feel like you could do a Sound of Music spin in the room.
Price. The GCH is too expensive for what is being offered, I think. You know how the AKL and WL are always cheaper than the Poly or the Contemporary? By at the least $100 usually more? The GCH should be that price. It's the same room size, same architect. You are paying a lot extra for that good location.
Location for the GCH is, I feel, it's only major selling point. But, from our experience, those hallways at the GCH are soooooo long! We stayed above DTD and had to walk down 2 long halls to the center of the hotel to get the elevator and then turn around and walk back, the same exact distance, to the hotel's only entry to DTD which was practically under our room. The room was pleasant but lacked that certain Disney Touch. I can't quite put my finger on it, but something is definitely missing in those GCH rooms. But, at the end of the day it was nice to practically fall into the hotel from DCA! We saw World of Color one night and were back in our hotel in about 10 minutes!!
And the walk from DLH can feel long sometimes, but you are walking through DTD - there's live bands, street performers, the monorail station, all the great shops and restaurants to look at. It's visually and aurally interesting, the area is alive. You feel that Disney magic when you walk through DTD.
If it's your first trip to DLR and you want to get that "only at
Disneyland" experience then perhaps you should consider the Disneyland Hotel for it's theming, lush tropical grounds, larger rooms and history. But, if convenience is a big factor, then you can't get better than the GCH. It is against DCA, you would only be closer if you were a Disney Cat living in the park!
Either way, you're staying at a Disney property so you kinda can't go wrong!! Enjoy Disneyland!!