The hotels in each of three locations were great, although definitely not as high end as ABD would use. We were at the Anantara Riverside in Bangkok which was beautiful and very well-located on the river, but it was not the Mandarin or the Peninsula which was fine with our family. I will say the breakfast at the Anantara was insanely good - even better than the Table Bay in South Africa where we stayed with ABD which had heretofore been the best breakfast ever. In Chiang Mai we were at the Rati Lanna which was a beautiful hotel in a beautiful spot on the river (and the spa was amazing). The only downside of the Rati Lanna was that it was a little bit outside the old town and not very pedestrian friendly. But we were so busy while in Chiang Mai that it really didn't matter, and when we wanted to go somewhere, tuk tuks were easily available and very inexpensive (and fun!). In Phuket/Krabi we actually stayed on an island between the two at the Paradise Koh Yao. The resort was remote, but it fit perfectly into the activities we did and we loved the location. It was not "rustic" by an stretch, but it was slightly more basic because of the remote locale. It had a great pool, insane beach and other fun activities (my daughter and I did batik painting our last morning and it was an unexpectedly special experience).
The food was good and plentiful. Thomson definitely includes more meals than ABD which we like, and the meals were for the most part really good. The lunch our first day in Bangkok is one that they should probably rethink, but other than that we had no complaints except that they should add a western meal in somewhere because 10 days of even really good Thai food is too much Thai food! Meals were mostly family style and the food was well-prepared and plentiful if a bit repetitive. In Bangkok we ate at the hotel (it was a lavish seafood buffet with a traditional Thai show), and because of the location we did the same at the beach (it was a different buffet each night on the beach which was very nice). In Chaing Mai I was really impressed that they picked beautiful and interesting restaurants each night, including dinner one night at an 80 year old historic restaurant on the river with more traditional Thai offerings which was very memorable. Soft drinks and specialty drinks were generally included and alcohol was included at several dinners as well.
Our guides were very, very good. They were knowledgeable, organized, fun and willing to do anything for you. They were all Thai natives and we enjoyed getting to know them, and found their personal insights into life in Thailand to be one of the best parts of the trip. With 3 guides, we felt more than taken care of, but I should note that we tend not to need lots of attention. I did make a couple of requests - I went back to the hotel early one day, and asked for help going back to the night market in Chiang Mai one evening and both times the guides did more than I would have asked to accommodate my requests. The only place I think our guides were not quite as good as some of the ABD guides we have had (Korey comes to mind) was in what I would call "storytelling" - imparting information at the right level of detail and making it come alive for all members of our family. In many instances our guides did that very well, but on our day in Bangkok I felt like our temple visits could have been more impactful if information had been delivered in a less detailed/matter of fact way. But in fairness, that was a tough day - it was hot, it was crowded and it is not an easy topic to impart to a group that mostly had no background knowledge. On the whole I was very satisfied with our guides. Also, I note that in Thailand there are significant limitations on non-native tour guides, and I wonder if that is why ABD has not entered the Thai market yet as any non-Thai guides would be required by law to be tour managers and not tour guides.