We've had cabanas in two locations - by the dolphin swim area and by the reef area. We were by the dolphin swim area when we had a higher level reservation, but I'm not sure if that's universally the case. There are also cabanas near the lazy river area, although we've never had one of those. The views were pretty much what my descriptions suggest - you look out at whatever water feature your cabana is near.
We love the cabanas, although I will acknowledge that they probably are not "worth it" for most people. Still, we like having a place for people to come back to, which helps when our teens are going off places by themselves. We also like having guaranteed shade and a private spot to be in. The private animal visits that come with the higher-end cabanas are really fun as well.
I don't know if you have any specific questions I can answer. We get a cabana every time we go to DC. I think you can have a great day there without one, but it helps enhance our experience enough that we always do it. We get cabanas when we go to Aquatica and on cruises, too, for what it's worth.