May Kaidee's 2 Cooking School
A vegetarian and vegan cooking school in the Sam Sen area north of Khao San Road. You'll shop at the local market to pick fresh ingredients and learn meat-free traditional Thai recipes as well as unique food such as the delicious pumpkin hummous. The owner has been an experienced vegan cook for many years and has a recipe book available for purchase. Those interested need to give at least a day or so advance notice if lucky, you can just try to show up at the morning session and they might let you in. The school also has a restaurant with many vegetarian dishes and as a guest house attached to it.
Sor. Vorapin Gym Muay Thai School
If you dare, you might want to learn muay thai Thai boxing. Beginners and walk-ins are welcome. Shorts and gloves are provided at the course. The English instruction may not be too detailed, but key phrases like "punch", "kick", and "one-two" are in place. Wear protection though! If this all gets a bit too heavy for you, it's also possible to sit outside and watch the trainings take place. Saves you 1,000 baht on an actual muay thai match!
Activities on Khao San Road are not particularly high class. Many backpackers just chill out in a cafe and watch reruns of Friends while sipping a cold Chang beer. People-watching is also a major activity; this can be done in many roadside bars and pubs along Khao San Road. When all this becomes too stressful, there are plenty of massage parlours around.