Hi, I just got back from a Singapore/Thailand trip. I was travelling from Australia so I booked a flight to Singapore which was cheaper and shorter flight than direct and then to Phuket for a week (have been many times and can recommend hotels/restaurants etc) and then a week in Koh Samui.
I think you should go to Thailand, the people are so lovely and accommodating and the food is amazing - very clean and fresh and there is so much do to. In regards to snorkeling there are many tours you can get when you are over there, they usually include lunch and take you to Maya Bay - which is where 'The Beach' was filmed, not far from there is where they take you to snorkel. Koh Samui is gorgeous but smaller than Phuket. I stayed in Koh Samui on Lamai Beach and the water was like warm bath water but very shallow and crystal clear.

Let me know if you have more questions.

In early November you may run into rain and choppy water. October is usually quite rainy, in November the monsoon shifts so that by the end of November, the weather in the Phuket area is lovely. So - as you already know - there are no guarantees about weather.

Malaysian Borneo is another place to consider. You would go to Sabah, flying into Kota Kinabalu from Singapore. There are world-class diving and snorkeling areas there. but the weather may be an issue there as well.

www.weatherbase.com for historical weather info.

weather can be a problem....i like the west coast of thailand: the khoa lak area gives you the similan islands for potential areas...

the jw marriott and the le meridien in k/l would be perfect for your honeymoon...

another potential would be the amari vogue not far from krabi