We found that having some excellent guides helps us to understand and learn more about a culture, allows us to look around more rather than concentrating on driving, introduces us to many foods and traditions, and that we wind up seeing and experiencing much more. While in Thailand we used 4 different guides...all good in different ways.
In Bangkok Mr. Oat was a walking course in Thai history. He was very knowledgeable, friendly, flexible in coordinating what we were interested in, and he was generous and thoughtful....bringing us bags of fruits for our hotel room and buying little taste treats. We particularly wanted to have the guide we hired rather than using an agency that sends different people. After 2 really good days with Oat, he was called away to his sick father and sent us a lovely young woman for the 3rd day, Nikki or Ms Nid. It actually worked out really well to have Mr. Oat as our introductory guide and history professor followed by the warm sweet Nikki for another point of view. Mr. Oat's driver was excellent with a wonderful car but speaks little English.
Joy was truly a joy. He is a warm hearted, knowledgeable, flexible man with a great sense of humor. We spent 4 full days including an overnight trip with him and found that not only did he include the important spots and those he thought of particular interest to us, but he was able to go with the flow and live in the moment when we found out of the way local markets and fascinations. He is a very good driver with an SUV and we felt very safe with him.
Paul Collins was our tuk tuk guide in Chiang Mai for 2 days and it was interesting to note that he is a westerner who was born and lived almost all of his life in Thailand. Using a tuk tuk for part of the time was a benefit since we felt less insulated than in a car but it is hotter and noisier. Paul too was thoughtful with many lovely thoughtful touches and small kind gestures. He too was very knowledgeable and helpful.
I recommend that you figure out and communicate what interests you so that guides can organize in such a way as to best meet your personal needs. We greatly benefited from each of these wonderful people.