I have never been to Thailand or Sri Lanka yet, but Bhikkhuni Dhammananda has a monastery at:
Songdhammakalyani Monastry 195 Petkasem Highway Muang District, Nakhonpathom Thailand 73000
Tel. +66 34 258-270 Fax +66 34 284-315
In Sri Lanka there are probably several choices as it is somewhat the leader in providing bhikkhuni ordinations.
In Sravasti, India there is Maha Upasika Bongkot's Dhamma center. A beautiful place with a huge meditation hall, kutis, several hectares of land, etc. There are about 108 men and women there, mostly women, who wear white and follow the 8 precepts. She also runs another facility in Thailand, but sorry don't know the address of that one.
edit: I have a list of bhikkhuni centers in Asia here:http://www.dhammawiki.com/index.php?tit ... ni_centers