Read the Hana threads under the Top Questions on the main page of this forum (use the full site). Once you find things that appeal, post an itinerary and you will get more help.
No must sees except what you want to see.
Hana will usually take a full day, so leaving by 6am is often a good idea. Most people don't recommend combining Mamas with the Hana day, showing up sweaty and tired is not the way to enjoy spending all that money.Edited: 13 February 2018, 06:33
When I lived in Kihei we would leave at 6:00am but we're morning people. We always had a 12 hour day exploring and going to Kipahulu to Lindberghs grave before making the return. You won't get far if you want to be back for lunch.
Here are a few online guidebook links that might help you get started. This guide is written and maintained by an author who lives on Maui and usually keeps his site well updated.
If you can go as far as Waianapanapa State Park, that is a wonderful stop. The link isn’t just about camping.
Keanae Peninsula is not as far as Waianapanapa, and can be a nice turn around. There is a nice arboretum there, historic taro fields, famous Aunty Sandy’s banana bread and more.
Garden of Eden is a commercial stop with entry fee, but very nice, and can be a good stop if you don’t want to go any further.
Twin Falls is close to the beginning of the Hana Highway. Yes, there are better places on down the road, but if yiu want a short taste of Hana Highway and not an all day trip, you might really enjoy Twin Falls. It gets very busy. I would head out very early and get there first thing in the morning to enjoy it to without the big crowds.
Look at downloading the gypsy app for gps satellite powered commentary as you drive.
Do you plan to get out and explore? Hike? Spend time on any beaches? If not, I’m not sure the drive is worth it. If so, you’ll be grungy and won’t want to stop at Mama’s directly afterward. Did you decide to skip Haleakala and Upcountry? Mama’s would work better after that road trip. You should be more rested and less sweaty or muddy.Edited: 13 February 2018, 07:25
lunch or dinner at Mama's
Sure_Caveat: Mama's May be Very Busy.
Enjoy RTHEdited: 13 February 2018, 08:23