West Maui is amazing, if you want value stay as close to Napili as you can, Napili bay is, IMHO, the best beach on this rock I call home. North shore is over rated, I say stay on the West side the 4 nights. When my wife and I moved here we lived in Paia...great shops and restaurants, but the beaches are just ok unless you want to wind or kite surf. You'll be here in the winter, but try to snorkel Honolua bay if you can. Take Trilogy on their boat ride to Lana'i if you can, well worth it.
Travaasa Hana is amazing......enjoy the drive there, enjoy hana, and drive the backside out.
Wailea Marriott is a great choice, it's a beautiful resort in Wailea and isn't as pretentious as The Grand or the Four Seasons. You'll love it. Drive down and snorkel Makena Landing if you can.....saw 23 turtles in one day there once....still my record. :-) Also get the "maui shot" at secret beach while you're down there. Hike Hoapili Trail King's highway" too....it's the most "recent" lava flow on the island....and count how many goats you see :-)
Feel free to txt me if you have specific questions, I work on both the west side and south side and vacationed here for years before we moved. Always happy to help others enjoy this paradise.