CDub06,
We were on Maui three years ago (April 2018) for our daughter's wedding, and we drove the road to Hana for the third time. The road to Hana is significantly better than it was in 1976 when my wife and I went there on our honeymoon. I would highly recommend going down the southeast side of Maui on the road to Hana, but as several people have said, you should leave by 8:00 AM and don't plan anything else for the day as you will often want to stop on the way there. Put another way, it is a full day trip if you really want to see everything.
We have never driven the backside to Hana or the south end of the island, and the road was closed three years ago so we couldn't do it anyway. However, we took a helicopter ride on Maui in 2018, and we flew over the south side of the island from the west end to Hana on the southeast side. The terrain generally looks like West Texas until you hit what I will call the rain line or the tree line. You literally go from no trees to lush trees everywhere as the southwest side of the island gets little rain and the southeast side where Hana is gets over 400 inches a year. And yes, the car rental agreements say you may void the rental agreement and be liable for damage if something happens when you travel on roads where they say not to go.
Personally, I would drive down the southeast side of the island on the road to Hana like everyone else, but just leave early. There are places to eat and to get snacks/refreshments along the way now unlike 45 years ago. You can also stop in Paia at the Hana Picnic Lunch Company and they will pack lunches to go for you. And Aunty Sandy's Banana Bread is definitely worth the stop in Ke-Anae, but you really have to get off the road to get to it.
The road to Hana is incredibly scenic as well as curvy. The bridges are narrow in some places, but not like the one lane bridges with little or no pavement 45 years ago. Some day I would really like to spend a couple of nights in Hana to explore and enjoy the area.
Oheo Gulch or Seven Pools is great, but as one person said, you can no longer swim in the pools. There are however pools and places in which you can swim on the way down. Charles Lindbergh's home and grave are past the Seven Pools area, but we have never been past that point.
Here are a couple of alternative suggestions on things to do:
1. Drive all the way around the north side of the island. From Maalaea drive up the northwest side of the island through Lahaina, Kaanapali, and Kapalua and then on over to the Nakalele Blowhole. Shortly after this point on the northeast side of the island, the official road ends and you are not supposed to take rental cars from that point on down to Kahului. But if you are willing to take the risk, keep driving down the northeast side of the island as it spectacular. In some places, the road is truly one lane and you are up on cliffs that are 800 to 1,000 feet above the ocean or the valley below. I had no idea how beautiful the northeast side of Maui is because hardly anyone goes there. And definitely go clockwise around the north side so you can hug the inside of the road if you have to pass anyone on the northeast side of the island.
2. Take a whole island helicopter tour of Maui (not the one that includes Molokai). We used Blue Hawaiian Helicopters (yes it can be pricey) and the trip we took flew around the north side of the island and then came back down the west side of the island and landed about halfway up Haleakala for a wine and snack break and viewing of the west side of the island. Then we took off again and flew up on top of Haleakala (no landing) and then down the south side of the island over to Hana and then up the east side of the island. My wife and I would tell you that this is one of the 2 or 3 most spectacular things we have ever done in our lifetimes. This is also true of our helicopter ride on Kauai years ago.
I hope that helps some of you who are planning to go to Maui.