I think the current land that White Water sits on is too small for everything that I want to see at the park. I think that what the park has currently is good, but not good enough to keep people coming for years and years. I haven't ridden Kapau Plummet because I wasn't at WW at all last season, I liked Bermuda Triangle though.
I think WW should change some of the things that they have. Ohana Falls is short compared to most family slides and I would love to see them make the slide longer. The waves in the wave pool are weak and I would like to see them make them higher. The Lazy River and their other slides (I don't have an opinion on Kapau Plummet) are fine.
As for new things, I would like a pool for just swimming and relaxing without the waves or current and maybe a kayaking/canoeing pool like Oceans of Fun has. (I understand they don't currently have enough room for these things.)
Things they shouldn't do: pools with swim-up bars like some parks have and going away from the theme of WW, even though it isn't as big of a deal as SDC's theming, it is still important.