Women travelers face no particular discrimination or dangers in Thailand. Women should, however, be very careful when dealing with monks: Never touch a monk, never hand anything directly to them (it should be set on the floor in front of the monk or given to a man who will hand it to them directly), and don't sit next to monks on public transport or in the monk-only designated areas in waiting rooms. Some parts of temples do not allow women to enter; look for signs indicating this.
Thais are extremely modest, almost prudish, and though Thai bar girls dress in scanty fashions, that's not recommended if you want respect. Women should avoid tank tops and short-shorts (the equivalent of wearing nightwear outdoors). Going topless on beaches is illegal in many areas and considered a public obscenity. At all temples and mosques, be sure to wear a long skirt or trousers and have your shoulders covered. Your head should be covered in mosques, but headwear (caps, sun visors) must be removed in Buddhist temples.
Thais love asking foreign visitors, "Are you married?" Thais also commonly marry quite young and start families early, so many assume unmarried travelers to be sad or lonely. Don't take it personally. Say you are married with children, and the questioning should stop.
Check out Journeywoman (www.journeywoman.com), an award-winning, "real-life" women's travel-information network where you can sign up for a free e-mail newsletter and get advice on everything from etiquette and dress to safety; or the travel guide Safety and Security for Women Who Travel by Sheila Swan and Peter Laufer (Travelers' Tales, Inc.), offering common-sense tips on safe travel.