Re: OP. On my first trip in 1996 I went by train and stayed at a cheap guesthouse (the Lek guesthouse?) that had some good treks to Karen villages. That turned out to be the interesting part.

On more recent trips I've flown and aimed for places like the Suriwongse or the Pornping that used to be at the top of the market but have been in the sub-$40 range. I think that's the sweet spot on value vs. price. I tend to favor the night bazaar area and walk to places near or inside the eastern side of the moat. Chiang Mai could do better on pedestrian accoms, IMO.

Overall there are tons of choices and the value is generally quite good.