The rooms in GCH that have true park views are right over the park, they are not high though so the view doesn't go across the whole of the park. But this is the only place you would be able to see true details of people walking and as the OP noted the GRR rafts. The park view rooms in the GCV have a better view and can see a bulk of paradise bay and the attractions around it.
DLH has park views from almost a third of the rooms. It is taller but further away. Also half of the rooms with park view are at an oblique view and only see a small corner of DL.
PPH has possibly the most and best view rooms. About half look across the street and over the lenght of paradise pier. Though they are not as close as GVC by any means you can see the motion of many of the pier's rides.