It's been several years since I was last there so I might be a bit out of date. If you avoid the overdeveloped parts (which are just depressing), much of the island is still lovely and with a decent amount of rainforest and wildlife.
Depending on your budget, I believe the Datai is the best resort on the island but there are many other good options.
Went last year and loved it, although I had very little to do with booking it (we went with friends who live in Malaysia) and only went for the weekend. We were in a villa but spend most of our time on the beach. The self catering really meant eating out as there were signs up in our kitchen saying don't cook! But the cost to eat out is very low compared to the uk it seemed pointless to stay in and we wanted to try the food which was amazing. Il try and remember the names of the restaurants we went too and come back!
Definitely Andaman, heaven. We have been to Datai, paid for as a corporate, its very honeymooney,couply and high end, but Andaman is more family orientated. They are the only two hotels on the beach. You can go and eat at Datai and put bill on Andaman bill. Spas at both are great.
Can't remember about vaccinations
The only thing is you would need transport to goto other areas, as these two hotels are on their own. But we were happy with that. We went out on the Mangrove Tour, excellent. The hotel does dawn and dusk wildlife walks which are really good, my ds loved those. Its really good that you have the beach and sea on one side of hotel and then the rainforest and wildlife on the other side.
Food was good, lots of little monkeys about, nice pool, slide etc for dd
Loved casa del mar - room opened onto the pool area and beach, it was amazing. Breakfasts were lovely as were the cocktails! We went into the street for dinner rather than eating in the higher end places, the seafood is so cheap, think we are lobster and crab for under £20.
I want to go back - best holiday I've had by far - and have six week old so not going to be able to do it again for about twenty years
We stayed at the Four Seasons in 2011, ok but lacked character. As we hadn't booked (or paid for!) the honeymoon "experience", no one congratulated us or made any extra effort despite being aware we were newlyweds.
The beach also wasn't great. Really wished we'd stayed at the Datai.
This was a few years ago too but loved the Bon Ton, a beautiful hotel where you stay in antique Chinese houses. Walking distance to a lovely beach and has a very picturesque pool. Hired a car to see the rest or the island - very easy to get around.
It's fantastic. We stayed right on the beach after flying over from mainland Malaysia for a mini holiday in a holiday!
I was gutted as we missed the opportunity to book a jungle walk to see the hornbills and was sat on the beach on our last day when I heard lots of chattering, looked up to see the tree I was sat under was FILLED with them! We also saw monitor lizards, lots of monkeys (with diddy 'ginger' babies), ate fantastic (very cheap) food, drank delicious star fruit smoothies and learned to batik by the sea front.
There was quite a bit to do if you wanted to be more active but as we had been backpacking for over a year at this point and had just got back from a rainforest stay in Taman Negara, we hit the relaxing 'beach holiday' side of it.