bldgs 1, 2 and 3 are preferred. but4 and 5 are not... they are equat distance between the main pool and el centro (well, maybe the maya pool is a little further walk...
if you stay in casitas or not, make SURE the walk THROUGH the casitas area.. NOT only along the promenade... when you leave El centro.. turn left INOT the area as soom as you can.. you will wlk along fountains, reflecting pools, a rotunda, etc.. VERY pretty and romantic at night.
we were in bldg 5 the first time we were there, and just dutifully walked along the promenade (along the lagoon....
one night hubby said "I wonder where THIS path goes???" (at Disney, ALWAY WONDER where this path goes) and we were so happy to discover this hidden area.
our 2nd trip we were in cabanas which is the most convenient.. but lacking in theming. our 3rd stay there, swe lucked out and were in casitas 3 3rd floor laggon view!!!!

(now it is preferred

) well even if you are not in those bldgs. buidgs 1-3 are connnected.. go up to the 3rh floor and walk around a bit, explore. you cross cat walks, look down on the fountains and reflecting pool and find yourself in the midst of the rotunda!!! (we like to explore)
have fun!!!