You can visit WnW one of the mornings. It's the same advice I give for the parks, show up early and be first into the gate. Hit the major slides before the crowds show up, then do the lazy river and wave pool stuff. They have a beer stand near the wave pool, wooo hooo.
We went July 6th this year, stayed 2 nights at the RPR and saw everything. Yes, the crowds are very busy in July, but the parks also stay open later. So you can visit a park in the morning, go back to the hotel and swim, then come back at 5pm as the tired are leaving. The other good thing with going after July 4th is you get to see fireworks at 09:50pm each night.
If you want to throw in WnW one morning, and really see everything, I'd say you need 3 nights at an onsite hotel. The RPR is the fan favorite around here these days.