We own in Ali'i, and have stayed in Banyan once (for a one night rental as an add on to our week).
The Coral Building is the oldest and doesn't have the views of the others. It also suffers from cross-ventilation issues (the other buildings have great breezes). But in April I don't think that will be an issue as it won't be too hot yet?
I can't speak for the Coral Building, but even if you end up in there, you're still in Hawaii! How bad can it be, all things considered?
Banyan building all faces onto the pool, so you do get pool noises during the daytime hour, though if it's not a time of school breaks I think it would probably be pretty darn quiet. The Banyan pool is lovely to look at. You feel more like a resort which some people love and some people could skip. Because it is kind of a "C" shape (but a very stretched out C), you can see the other balconies in Banyan from your balcony. So no acting like honeymooners out there!
I did notice that the Banyan 2 bedroom we had had both bedrooms at the back of the unit. That means they don't face the ocean. You have more of the living area facing the ocean, but your bedrooms face onto the walkway out back where people enter their units. This could possibly give you more noise if the parking lot was noisy at night (we've never personally found that to be the case) or if someone is noisy coming back to their unit. We've usually found that due to the time difference (and the generally laid back nature of Kauai) most people are in bed or at least quieted down quite early. Not like the area is exploding in nightlife!
The Ali'i Building is straight, so you can't see onto the other balconies from your balcony. This makes it nice for sitting in your robe and pajamas and eating breakfast on the balcony! The Ali'i 2 bedrooms have the master bedroom facing the ocean, which gives you the best night sleep listening to the wind and the waves. But you have less of a view from the living areas (the living room faces the ocean, the kitchen is at the back of the unit and has only a distant view through the living room of the ocean). The 2nd bedroom faces onto the walkway/parking lot. We stick my father (completely deaf) and boys (who could sleep through a nuclear war) back there and they never hear a thing. There are a lot of palm trees along the back of both the Banyan and Ali'i Building which when the wind blows (which seems pretty much constant at night) makes a wonderful noise that sounds like a heavy rain and is very soothing and potentially covers a lot of noise.
If construction is going on back at the development behind LBR, any bedrooms facing the back/walkway/parking lot will hear it starting up at 7 a.m.
Hope this helps!
