I want to do some research on Thai historical figures, specifically the Aphaiwong Family, and wondered if anybody could recommend which libraries might be best for me to visit in Bangkok. I can read English and Chinese but only just starting out with Thai.

Any advice would be most appreciated.

http://www.siam-society.org/library/li_index.html

maybe neilson hays as it's an older collection, check university libraries, 
e.g. chulalongkorn and thamasat though you'd contact them first.

I think you could try to contact the Abhaiwongse family to
see if their archive is deposited in an institution;
many of these families keep on to their archives themselves.

Edited September 7, 20197 yr by orchis
added 'as'

I think Thammasat University is renowned also for historical studies. They have two campuses in Bangkok: Tha Prachan and Rangsit. Try getting access to their libraries.

Edited September 7, 20197 yr by Camillof

Map as Libraries in Bangkok

Thank you for all of these very helpful answers.

I will start planning my trip to BKK.