You’ve had some great recommendations in this thread already, and I figured I’d add my 2 cents as I lived on Maui for 3 years (lived Kihei; worked in Lahaina/Kapalua/Napili). I also had my honeymoon in Maui and stayed in Kapalua.
Dinner: 1. Mama’s, 2. Merrimans, 3. Plantation House, 4. Fred’s Mexican Cafe (if a Tuesday), 5. Royal Lahaina Luau (@ Royal Lahaina Resort)
Lunch: 1. Da Kitchen, 2. Fred’s, 3. Aloha Mixed Plate, 4. Plantation House
Dinner: Mama’s will require a LONG drive at night (think 45-60 minutes at least). Merrimans was our favorite dinner of our honeymoon (I never went as a resident because I lived south side). Plantation house is close. Fred’s is also a long drive but have an incredibly popular taco Tuesday that will involve waiting for a table. I always thought Royal Lahaina’s luau was best and I’ve been to all of them.
Lunch: Da Kitchen is the best by a mile. I ate here and Fred’s more than anywhere as a resident. There will likely be a line for take out and seating. Aloha mixed plate will be close to you. I very regularly purchased poke bowls from delis in Lahaina and ate at the beach on lunch breaks from work. Those types of items are usually always fresh.
Island activities: if sunrises are your thing, by all means go to Haleakalā, but I have always thought it was overrated and am willing to die on that hill haha. You also have to go so out of your way for just the sunrise….. but again, if that’s your thing then yes it would be worth it. I worked quite a bit in Makawao and Kula and it is not as catering to tourist stuff either.
1. Hana - Go, go EARLY (like leave Lahaina at 6am) make a day out if it because you will need the whole day. It has kind of become overcrowded, but I don’t want to deter you from going. It was so much more crowded on my honeymoon than it ever was when I lived there. It’s still so worth it. Drive it yourself and do not do a tour so you can go your own pace. If you want a Word document of every mile marker of the Hana Hwy just message me. I made one I pass along to anyone going to Maui for vacation.
2. Snorkel at Honolua Bay in Kapalua. My favorite snorkeling spot on the entire island and it will be close to you. I’d even go twice since it’s close. Go early as it starts to get crowded by lunch. Again I have mile markers described as you sort of just start to see some cars parked in the side of the road and it walk a bit through trees.
3. Cliff jump at Black Rock. Again you are right there in Kaanapali so might as well. I always liked stand up paddling here too so if you are a beginner rent some boards it’s a decent beginner spot (not great for any surfing though). If you have kids this is also a good spot. Waves can be tough at times for kids (and adults - make sure not to try jumping over the wave when getting in); if you go a little closer to black rock it’s easier to get in.
4. Fleming Beach - if you have kids this is a good kids beach that will be close. It’s near the Ritz and the Kapalua golf course (the one pga event is on)