One Night In Bangkok (or Chiang Mai)

At the end of the week, I'm going to Thailand for a couple of weeks. It's a family trip, not a retreat pilgramage, but I still hope to spend a couple of half-days in meditation centres. Last year, I spent a couple of half-days at Wat Mahathat in downtown Bangkok, which has a Mahasi-inspired meditation centre that is welcoming to both local and international visitors.

Does anyone here know of other centres in Bangkok or Chiang Mai that would welcome short-term visitors in this way?

Has anyone ever actually taken instruction at Wat Mahathat? I was encouraged to ask practice questions, but was too shy to ask.