I proposed to my wife in Hawaii, so our trip there is a very happy memory. But I don't think anyone can argue when I say Hawaii is one of the most beautiful places in the US.

Hawaiian Sunset
Sunset over the ocean in Maui.
From atop Mount Haleakala the sun comes up over the clouds.
Cycling down Mount Haleakala, here's an overland view of the island, with I believe the city of Kahului in the distance.
Volcano Mist
On the Big Island of Hawaii we stayed at a little cabin called the Volcano Mist Cottage. Beautiful little private spot, on the edge of Hawai'i Volcanoes National Park.
In Hawai'i Volcanoes National Park, this is Halema'uma'u crater of Kilauea one of Hawai'i's active volcanoes. At night the the smoke glows red from a lava pool under the rim. Unfortunately we couldn't get a good night-shot of the crater with our cameras.
Lava coastline
Still in Hawai'i Volcanoes National Park, lava flows years ago ran down the eastern part of the park. The coastline here is all volcanic cliffs, beautiful.
Road Closed
This road used to lead to the northern entrance of Hawai'i Volcanoes National Park, but since 1983 there has been lava flowing from Pu'u'O'o that has close off this road.