We've stayed at all three, and PPH is definitely our favorite!
It has nice big rooms that are nice and bright, the colors are fun and happy, and parts of the lobby area smell like suntan lotion (they pump in the smell).
The pool is very basic and the slide isn't actually attached to the pool, but that would be a bonus for your daughter since she could go on it (while even wearing a life vest, unlike at the other hotels' big slides, if I recall correctly about PPH's) if she wanted to.
To get to the parks, you go out the FRONT door (don't follow the signs to the parks! I promise they will steer you into the path of consumerism, aka all the way through DTD), turn left, cross at the crosswalk. Go in through the Grand's big beautiful sliding doors!
If you're heading to
Disneyland or just want to go in the front gates of DCA, turn left down the hallway (I think the sign here points you to DTD, and that sign is fine). Walk down the hall until you see sliding glass doors on your right, go outside, follow the path, and you'll find yourself halfway through DTD (across from Haagen Dasz, next to Sephora). Turn right and get to the esplanade!
If you're on your way to DCA, since you're an onsite resort guest and it's allowed for you, go through the Grand's lobby and follow the signs for DCA. That DCA entrance brings you out close to Grizzly River Run (which is where the FP machines for the World of Color are).