1. Driving up to the summit of Haleakala. I've gone both at sunrise and during the day. I actually preferred the daytime. Sunrise was great but freezing cold too. The summit is over 10,000 ft rising from sea level so it's an amazing view either way.

2. I'd do the road to Hana. It's a beautiful drive. The black sand beaches at Waiʻānapanapa State Park are cool. The pools at Ohe'o Gulch are great too. Just the experience of that drive is something you'll always remember. Just don't be in a hurry to get anywhere.