Starting on the south side and going clockwise, for the first ten miles (between Maalaea and Lahaina) the road stays close to the beaches, and then after Lahaina the terrain starts getting more and more mountainous. These early beaches (the southern beaches) are mostly sandy in gentle terrain, a lot like the north Kihei beaches. But unlike Kihei, there are no towns anywhere near these beaches, which give them a more remote feel, like you'd expect from a tropical beach.
Once past Kapalua, the gentle sandy beaches disappear, and the drive turns into a rugged mountain trek. However, the few beaches along the north shore are spectacular. Like the south shore, most of the beaches are separated by rocky outcrops that jut into the water and when they submerge turn into a reef. These outcrops shelter the beach, making it good for swimming and make the rocky edges good for snorkeling and fish.
Maui Hawaii Travels 2002      
The 60 mile drive around West Maui is a spectacular trip of almost nonstop beaches. Though it doesn't look that long, it's an all day trip because of the rugged terrain on the north side.