Because of it's location, Paradise Pier is the only hotel with a view of World of Color. The exception is the GC Villas (you would have had to of rent points for that, and typically reserved before this time to get those rooms--the villas at GC rent about 11 months out)--some of those have a WOC view.
The Grand Californian is a very low slung hotel (only 6 floors--and the 6th floor is only for Concierge, I think)--so it doesn't have many view rooms. We overlooked downtown Disney before, and so we had a good fireworks view from our Grand Californian 5th floor room. The
Disneyland Hotel and Paradise Pier Hotel both have lots of floors (DLH is 14 stories tall with skyscraping views on many sides). From the Disneyland Hotel you are either looking at DLR (so Fireworks view), the pool, or parking lot/city view. The Paradise Pier has a wonderful view on one side of California Adventure--and this is the upgraded "theme park view". Paying extra for this experience really adds to the stay, because that view is pretty good. My kids actually love to look out the window at the Disneyland Resort Hotels, so I think the view is worth it.
Here is what the theme park view looks like at Paradise Pier Hotel:
http://www.startedbyamouse.com/startedbyamouse2/Club33TripReport.shtml
I have stayed at all 3 resort hotels, and they all have their good points. We are going to stay at the Paradise Pier next month for our Halloween Party stay--and I upgraded to the theme park view and concierge. I want to take the headache out of trying to get food--and just have it available for us there at the hotel and look forward to checking out the PP concierge service.
Have fun!
Lisa