Any recommendations for thai textbooks targeted to thai language learners wanting to go from beginners to intermediate?
My top three, that I would say are 'must haves' for the intermediate learner would be:
Thai: An Essential Grammar (Routledge Essential Grammars) by David Smyth
Thai Reference Grammar: The Structure of Spoken Thai by James Higbie
A Reference Grammar of Thai by Shoichi Iwasaki
What books are you aware of or already have ?
You might start with Benjawan Becker's for beginners
sort of depends which system you might prefer or your goals