I agree, West Maui is wonderful, I love it there.
However, I'll make a couple of comments about Kihei, which is a charming (in a funky way) little town in South Maui. We stayed in Kihei (at our Worldmark) as our main location for years, only in 2008 did we move up consistently to Kaanapali (West Maui).
Kihei has a wonderful set of beaches (Kamaole I, Kamaole II and Kamaole III) and is also right next to Wailea, which has stunning beaches. I actually prefer the South Maui beaches to West Maui beaches.
Second, Kihei is a terrific place to use as a base camp to explore Maui. It's very central and if you wish to visit Haleakala or Hana, it is well located (in addition to visiting Wailea). Further, you can easily drive up to West Maui (Lahaina/Kaanapali/Kapalua) to visit.
There are a number of timeshares in Kihei, they lack the amenities associated with the nicer timeshares in West Maui (Marriott and Westin). The other thing about Kihei that is relevant is that the wind kicks up in the afternoon, and if you're still at the beach when the wind kicks up, you have to hurry to pack up because it can be unpleasant. We learned to start packing at 1:30pm even though there was no sign of winds, because by the time we were fully packed, it was time to go.
So.....both locations have their merits and I love both and would stay unhesitatingly in either.
Good luck and enjoy your trip!
Best,
Greg