Not sure if you've been to BKK yet, but I just got back from a great trip to Bangkok and Ayutthaya. I used a tour organizer called BKK Tours (http://www.bkktours.com), run by a husband and wife team. They specialize in organizing tours for singles and small groups and were just fantastic! They have a lot of positive reviews on TripAdvisor and will tailor your tour to your interests.