I don't have one favorite spot because I like to see new places, but Hawaii was probably our best ever family vacation. It was beautiful and had a mix of activities--hiking, marine life, snorkeling, beach and pool and volcanoes. That's a pretty long flight for you. They do have a new Disney-owned resort there though that could satisfy beach and Disney lovers. We have the same dilemma--I like the beach, my husband prefers the mountains.
Southern California could probably satisfy at least three of you. It has mountains within reasonable driving distance, the beach AND Disney. We've had a couple of good vacations in LA, San Diego and Carlsbad.
We went to the Grand Tetons and Yellowstone last summer. The Grand Tetons would obviously satisfy your husband and Jackson/Jackson Hole has a variety of activities for all interests. No beach, but would whitewater rafting help? My boys (also 12 and 15) actually preferred the Jackson/Jackson Hole part of the vacation to the Yellowstone part.