No appointment necessary, we walked into the Chiang Mai Hospital and saw the doctor within 15 minutes. He prescribed the Japenese Encephalitis vaccine and told me I don't need the Rabies shot, just don't touch dogs. I forgot to ask about monkeys.
The doctor visit and the first of two J.E. shots cost about $25 US dollars. In the states, the travel clinic wanted to charge me $50 for the doctor visit and $109 for each J.E. shot... You can get malaria pills at any pharmacy here - no prescription necessary. Last I checked, malaria pills ran about $11/pill in the states and taking one a week will break my bank. I will get mine filled over here.
Moral of the story: come to Thailand for all your health needs. Endorsed by me.