Hawaii is a great winter destination, a way to avoid Austin’s cold and wet weather. You can fly from Austin to Phoenix on several airlines, including my favorite Southwest. Then fly non-stop to Kona-Kailua, on the Big Island of Hawaii, for just $418 round-trip on American. You can find the details in this Secret Flying post.
There is lots to see and do on the Big Island, including Hawaiʻi Volcanoes National Park, Puʻuhonua o Hōnaunau (city of refuge) National Historical Park, surfing, snorkeling, shopping, hiking and visiting the giant telescopes at the Keck Observatory on top of Maunakea.
There is also Kohala Ditch Adventures, a sort of flume ride in irritation canals that pass through long tunnels and exposed channels, several miles in total length, on the north side of the island.
The Big Island is well worth a visit.