Summary: a great unit generally, would highly recommend it for families due to its layout.
My wife, two children (aged 6 and 2), and myself stayed for almost two weeks in Kelly's unit. We had a great time and it was well-suited for our family.
The unit is in building 3 on the 4th floor. Building 3 is the quietest and the highest, but it's also furthest from the beach, so there are trade offs. The walk to the beach isn't very long, but there's a decent hill which is only problematic if you're pulling two kids and a ton of beach stuff in a wagon. I think the views from this building offset the distance from the beach overall.
We spent an inordinate amount of time on the balcony whale watching. The view is gorgeous.
The unit is unique in the maui vista in that the loft has been closed off from the rest of the unit. The loft bedrooms are usually quite loud and get a lot of sunlight. We preferred this set up as it allowed us to put our kids in the twin beds off the main floor and keep the upstairs bedroom for ourselves. If you have a young family and are staying at the maui vista, I can highly recommend this space.
There a number of beach chairs and beach toys. There is a fully equipped kitchen (with a coffee maker, thank god). The beds are comfortable and there is a good sized kitchen table.
There is A/C, but you really shouldn't use it unless the place is scorching - it's Hawaii! Turn on the fan and enjoy a beer.
All in all, we'd stay here again in a heartbeat.