In general I would say, Pattaya is rather not the best place to learn ANY foreign language.
Bangkok would offer a lot more options.
Also, it depends what your budget is and which level of proficiency your wife actually wants to achieve.
Everyone's learning pattern is different, and me myself I rather prefer group classes at a moderate pace (that is how I managed to learn Thai), but for people who are very focused, determined and have the necessary budget, private 1-1 classes definitely make sense. If you have suitable books and materials, you can create a "class structure" with systematical teaching even in a 1-to-1 learning environment.
I have been teaching German 1-to-1 to a Singaporean woman who was married to an Irish guy 8 or 9 years ago, they were about to move to Munich where the Irish guy was offered a great management position.
The lady (a smart one) managed to adopt the grammar quickly, but it took a longer time to work on the pronunciation. In the end, they were happy with what they got and the lady had a good base to start daily life in Germany and improve her skills there.