Because the government is presently completing conversion from one set of coins to another, the coinage is confusing. Most public telephones now accept the smallest one-baht coin. Thai currency is about 35 baht to a US dollar at the time of publication. Government rates are also posted at banks and exchange kiosks . There is no currency black market.
Hotels generally give poor rates, so change money at a bank.
You will get better rates for travelers cheques than for cash. Bank are open from 8.30 am. Banks also operate exchange kiosks all over Chiang Mai. Credit cards and Tipping Major international credit cards are widely accepted in hotels, restaurants and shops. Tipping is widely practiced.