The Ritz is a much nicer property. The challenge with the Ritz is the location. It is super windy, wet and much colder than the Wailea Marriott.
The Wailea Marriott is older, rooms are not so nice. But what the Wailea Marriott offers is the ability to walk to a dozen great restaurants, much drier and warmer weather. We had a oceanfront at the Wailea Marriott. We like to sleep with the patio door open. What we discovered is that people step out on the patio and smoke all hours of the night, and the smoke comes right in your room.
A big plus at the Wailea Marriott is the ability to rent a pool cabana for the day, 100 per day (75 if you are a gold or higher). If we were to return to the Wailea Marriott, we would select the least expensive room, hope for an upgrade, and spend the difference on the cabana. The cabana is inches from the infinity pool and overlooks the pacific. Super nice. Reserve the cabana for the days you are staying at the Wailea Marriott, and pocket the savings for days you are sightseeing.