Maui
Maui is called the Valley Isle, because it is formed from two volcanoes, Haleakala and Kahalawai. Haleakala a giant dormant shield volcano, at 10,023 feet above sea level, it gets the most attention, since it is an immense volcano that dominates the Island. Measured from it's base this is a mountain that is taller than Mt Everest. Kahalawai is normally referred to as the West Maui Mountains. The Haleakala National Park is a 24,719 acre wilderness area that takes up a sizable part of Maui's 729 square miles.
The population is 144,444, plus several tourists, who are generally found hanging out on it's great beaches on 120 miles of coastline. It has three airports, but the main airport is in Kahului (OGG) on the flat area between the two volcanoes. If you are looking for a condo, this is a good Island to choose, since there are many good options.
If you are staying on Maui, you will probably be staying on the West side of the Island. Driving Southwest out of the airport you will come to the township of Ma'alaea. Going West from there you will first come to Olawalu, then Lahaina, then Ka'anapali, Honokowai, Kahana, Napili, and Kapalua at the North end of the West Island. These are all hard to distinquish, unless you happen to see a flower covered sign along the way. The two port cities are Lahaina, which is the center of the tourist traffic, and Ma'alaea, which has a nice Ocean Center. Going South out of Ma'alaea will take you into Kihei, then Wailea and finally to Makena.
Maui is a great Island for hiking and ziplines. There are many miles of trails to explore and activities for all ages. Lahaina is the only place in the Hawaiian Islands where you can take a ferry to other Island. One departs to Lana'i and another one to Moloka'i.
The Northeast end of the Island is jungle and the South side is arid. The road to Hana is a great drive with miles of tree covered roads and one-track bridges. Even though it is only 53 miles, it will take most of the day to visit, since you will want to stop often for pictures.
A 7 day trip to Maui, will just motivate you to come back.