I am a huge fan of the Grand Californian. It is awesome. It is close. It has wonderful rooms. It is the best!
If you are able to get discounts then I think you will really enjoy the GC a lot!
I stayed at the Paradise Pier in 2004 and left it early and switched over to the GC. I was not impressed by the PP then. I did just stay at the PP in December and it was much better this time around. Oh, and I wanted to add that the PP really isn't as far away as some of the DH buildings though, because I always took a shortcut through the GC from the PP to get to the parks/DTD. If you choose the PP, make sure to take the shortcut!
I think you will have a nice time no matter which hotel you choose, but the GC is awesome...