Review: Southeast Asia Honeymoon, Thailand & Cambodia, Ayutthaya, Chiang Mai, Phnom Penh, Kanchanaburi, Bangkok

I'd probably spend one less night in Khanachanaburi and one more night in Ayyuthaya just because we were so charmed by it (not a fault of the itinerary—we just connected with that city and would have loved to spend more time).

I also would have only visited the mountaintop temple in Chiang Mai and would have replaced the other city temples with a more diverse itinerary like a food tour or hiking and waterfalls. 

Also, once flights become available from Phnomh Penh to Hong Kong, I'd go directly from Song Saa there. It would have cut out additional travel time, simplified flight transfers and allowed us to spend a night in another city.