The parking lot section that is by Paradise Pier Hotel just across from Paradise Pier(land) is large enough to put a decent sized water park. In fact it is just slightly bigger than the footprint of Soak City by Knotts.
Since it hardly ever gets used and the resort could use a small water park why not build a small victorian themed water park?
The water park would have 2 entrances... a themed main entrance and then a side entrance thru PP Hotel. The hotel itself would have to be demolished and rebuilt - to a style that would fit both PP(land) and the new adjacent water park.
The new hotel would be more "U" shaped with the main lobby near the traffic circle of Downtown Drive and Paradise Pier Drive. A new small parking structure would be built adjoining the hotel(next to what was the hotels original parking structure).
Paradise Cove would consist of a small wave machine, lazy river, and themed slides. The lazy river would circle a small island that would be accessed from 2 foot bridges which would cross the river. The island would have a small children's play area and a beach type "lagoon" entrance that would leave out into the lazy river.
These changes and additions would help with 4 things:
(1)a hotel that blends with Victorian theme
(2)satisfy people's need of a Disney water park, but still small enough to be ok with sitting empty during cold months
(3)increase foottraffic to Downtown Disney