I love the Coral Reef, especially for lunch. I've had a different seafood dish each time I've visited and all have been great. Service can be slow, so plan ahead for that, especially if you want appetizers and/or desserts. At peak times, even the wait for a table can be rather long. The dining room can be rather loud because you are literally sitting in a fish bowl and sound reverberates like crazy. The views of the tank are nice, though, and being a party of two, you are pretty likely to get a table right near the glass. Of the four times we've been there, three times we sat at a two-top directly in front of the tank.
I'm not a fan of the Wave, but I recognize that I'm in the minority. I find the menu to be boring, service middling, and the atmosphere of the dining room to be completely devoid of personality. It's like a nicely appointed cafeteria. Beige and bland. The lounge, however, is beautiful. I like going there for a drink. I believe they serve the restaurant's appetizers there, if not their full menu, so you could eat there if you're so inclined.
I've never dined at a character meal or buffet at Disney because they don't interest me at all, so I can't help with Crystal Palace.