I know you didn't ask for itinerary advice, but this isn't a great plan. You will lose at least 3 of 9 days in Thailand with your current itinerary. This is not a good honeymoon, regardless of how fit or young you are. Trying to see everything in a small amount in time generally results in seeing nothing at all. Thailand isn't going anywhere. I would personally pick Samui over Bangkok, but that is really a city vs. beach destination decision that is up to you guys.