There are rooms with superb views of the London Eye and beyond. These rooms are on the higher floors (about 8 and up) and are directly opposite the lifts. See the photos in my recent review, for example.
You need to upgrade your room to an Executive Studio-City View and you should specify your request for a London eye view in the booking. You need to book directly with the hotel at the Park Plaza website and not via an agency.
Unless you pay for a London eye view (guaranteed) then you cannot be sure that you will get one. I would guess there are about 10 or so rooms with this view.