We will be in Maui in March. We want to have 3-4 4 hour outings with our rental car that make the trip "special". We don't want a nut farm or rum factory tour.

Also 3-5 best dinners for $100/couple on Maui? What type of food and what should we order??
Thanks.

volcano

On your way up or down the volcano. Stop in Makawao a charming little town in Maui's upcountry.

It's definitely worth it to see the sun rise at the top of the volcano ... as long as it's not too foggy.
Also, this is longer than 4 hours, but it's very worth it to drive all the way around the island on the Hana Highway. I honestly didn't like Hana itself that much, but the waterfalls and views of the coast on the way there are magnificent. Be sure to stop at Oheo (7 Sacred Pools).
The Maui Ocean Center aquarium is pretty cool, and so are the towns of Lahaina and Paia.

Two restaurants I enjoyed were Manana Garage near Kahului and Nick's Fishmarket in Wailea at the Fairmont Kea Lani.

I suggest buying the Maui Revealed guidebook - very very useful advice.

Iao Valley
Haleakala Crater - doesn't matter if it's for sunrise or later in the day.
Drive up the west coast north of Kapalua and around to Wailuku.

Many threads here about good food. This last trip we really loved Mulligan's in Wailea. Nick's was also very good, but we did not like the highly-rated Sarento's (after paying a fortune!)

i also enjoyed the self-guided historic walking tour around town in Lahaina. not knowing where you are staying don't know that this will take 3-4 hours or even be what you have in mind.