I have good friends who married here on the mainland and took a two-week honeymoon to Hawai'i. I forget where-all in the islands they went, but they travelled extensively everywhere other than the Big Island. They rated the sunrise at Haleakala and the bike trip down as the pinnacle of their trip (no pun intended).
But, it's quite the investment in time to make it happen, to wit: The drive is some 30-35 miles from the outfitters and it takes over an hour to do the drive-up. Sunrise at sea level there near the equator is always within a few minutes of 6am (and, you'll find, sunset is always around 6pm). Haleakala's peak is at 10,000', so the sun gets to the horizon shortly after 5am. To catch the colors and glow before sunrise, arrival shortly after 4am is indicated. See where I'm going with this? My friends left their hotel at 12:30am, were outfitted with rental coats, filled out forms (disclaimers, mostly, at least one tourist dies each year on the descent), got the safety lecture,and piled into vans and departed around 2:30am. A short hot breakfast at the summit as the daylight started to arrive, around an hour, hour and a half enjoying the rising sun and temps warming up a bit, then the bike ride started. The bikes are big, fat tire rigs with HUGE disc brakes. Even with only a handful of rest-stops, it's around a 4 hour descent. They got back to their hotel around 1pm and collapsed the rest of the afternoon.
If I get to Maui, you can bet where I'm going first, sir.