I have stayed at both and they are both great, but different classes of great. The Ritz is a typical resort Ritz and is spectacular with great service. The only downside to me was the quarter mile hike to the beach. (Hey, if I am paying $16 for a Mai Tai I don't want to sweat it out hiking up the hill on the way back to the hotel!). No upgrade, it was before Ritz was part of MR.

Wailea is a great property too. Definitely not a Ritz, but very nice. Mrs. SoCal811 loved the adults only infinity pool and we spent most of our time there. Also, I think the views are better in Wailea than Kapalua or Kaanapali (no islands in the way). Whale watching was INCREDIBLE off the Wailea coast, but if you are going in August they won't be in season. Wailea is also about 100 yards from shopping and restaurants. I did get an upgrade here but the "ocean view" upgrade meant I could see the ocean if I stood on a chair in the corner of the balcony. Got 5 nights for 100k. Not bad.

Enjoy and congratulations.