Haleakala (House of the Sun) on the island of Maui, a truly amazing place above the clouds. If you get the chance to go then take it, but also take some patience as the drive to the top is a long and winding road. (The image above is looking west at the peak of Mauna Kahalawai in the West Maui Mountains).
The peak stands at 10,023 feet and looks out over a barren wasteland of volcanic rock. Getting up there does take some time as the road is very slow going. The speed limit on the Haleakala Highway in most places is between 15 and 20 mph and there are lots of blind turns (I counted somewhere around 30 blind hairpin turns), but about half way up you begin to rise above the clouds, which is really cool.
If you're not use to altitude then you'll definitely begin to feel it. We stopped at the visitor centre at around 7000 feet to use the bathroom, and as soon as I got out of the car I could feel how thin the air was; a bit more difficult to get a full breath and a slight pressure in my chest. Up at 10,000 feet was very noticeable. You do get used to it, but you have to take slow deep breaths. It can be very disconcerting if you haven't experienced it before.
We also got really lucky with the weather. We had a clear day, very little wind and no rain. I have heard of other's experiences up there in the blowing wind and rain, and very cold temperatures. When we left Ka'anapali the thermometer in the car read 82F (27C), at the summit it read 49F (9C). I suggested to my my wife that she should bring her winter mittens, we already had our winter coats going down there from Canada in February. I was pretty ok in a t-shirt and hoodie, and my wife was happy to have had her winter coat and mittens.
So make sure you put this on your travel bucket list...it is worth the drive, trust me!