We have requested and gotten Waianae tower overlooking the pool complex both times we have stayed at Aulani. I like this location as it is a quick trip down to the adult pool where we spend a lot of time, and coming out of the elevators on the lazy river side of the building puts you near Rainbow Reef, where we were able to get wristbands and towels with no line.
The main reason I like overlooking the Waikolohe Valley (that’s the name of the lazy river pool complex) is that we like to sit on our balcony in the evening, and we have been lucky enough to clearly hear the live Hawaiian music from the Olelo Room while sipping a cocktail in our PJs on our balcony. Heavenly! (For what it’s worth, we cannot hear any ambient noise inside the room with the sliding door closed)
I would focus your room request on the features that are more important to you rather than requesting a specific tower. For example, my request was “highest floor possible overlooking Waikolohe Valley, Waianae side if possible” but if being close to the elevator or overlooking the luau lawn are more your style, you could certainly ask for those. My only other tip is to make sure you’re not asking for a room location that’s not in your booking category - for example, if you ask for a high floor overlooking the Waikolohe Valley and you’ve booked an Island Garden view, they’re not likely to be able to honor your request and the room assigner won’t know what you’d actually want that’s in your booking category.