Sounds similar to Chiang Mai and the trekking isn't all that different either! As with Chiang Mai, there's an in-town attraction that is worth swinging by beforehand -- the Hilltribe Educaition Centre -- which has a very good selection of displays and detailed information on the surrounding tribes. Chiang Rai is the second busiest trekking centre in Thailand, so there's a wide variety of trips available with day trips along with one-, two- and three-night treks available throughout town. The longer treks should include a rafting segment. There's a mix of minority groups in the area -- predominantly Akha, Lahu, Sham and some Karen -- and the longer the trip, the wider the variety of villages you're likely to visit and stay at.
One of the most isolated towns in Thailand -- at the end of a 165km-long mountaintop road -- Umphang has been a long-running and very popular destination with Thai tourists, but never really hit the top of the pops with Western visitors. Unlike northern Thailand, where there is a mixture of different minority groups, Umphang and its surrounds is almost uniformally Karen. A typical three-day, two-night tour will encompass Umphang's famed Tee Lor Su waterfalls where you may camp the first day, and should include an elephant ride, rafting, visiting and sleeping in a Karen village. Trekking in the Umphang area is quite hard work and you will need to be relatively fit and healthy. Solo travellers may have to wait a day or two to rustle up a group.
Forming the southwest corner of the Mae Hong Son Loop, Mae Sariang sees a steady trickle of travellers passing through, but it really has all the goods to be a destination in its own right. Its proximity to the Salawin national park and the same-named river (which forms the Thai-Burmese border in these parts) makes for some excellent wilderness. Most treks will include both a hike in the national park and a rafting excursion along the river, often with time spent in the wildwest border town of Mae Saem Leap. The minorities in this area are predominantly Karen. The main issue with trying to trek out of Mae Sariang is that because few people stop here, you'll have problems rustling up a group. Of course you can just bite the bullet and pay more to trek solo, but if you're trying to keep the budget under control, perhaps try and get together a group in Mae Hong Son or Chiang Mai and then head here. The riverside scenery is spectacular.
Home to six national parks, Nan is a dream come true for wilderness lovers. We did a fascinating two-night caving trip out from a small village near Doi Phuka National Park, but there are also operators in the provincial capital, meaning you don't need to run the risk of not being able to get a group together. Nan has a large Hmong population and is also one of the few homes remaining of the M'labri people. Rafting is also an easy add on here -- especially in the wet season when the rivers are positively raging. While Nan isn't on any tourist highway, it gets a steady enough trade that you shouldn't have to wait too long to get a group together.
Phu Lang Ka
Another remote, in-the-middle-of-nowhere destination, Phu Lang Ka is set in the shadow of Tham Sakoen National Park and boasts some tremendous scenery of limestone karsts dotted across a mist-soaked valley. The trekking takes in the national park and the immediate surrounds of the solitary guesthouse in this part of the world. Minorities are mostly Yao and Hmong, but unlike other areas there's little in the way of "added extras": No rafting or elephant riding in these parts. You'll also need to bring your own group.
For a location so close to Chiang Mai, Chiang Dao has stunning trekking possibilities and there's a full range of options, from some hardcore trekking/climbing combos to gentle walks in the woods. Caves, viewpoints, minority villages (a mix of Akha, Lisu, Lahu, Karen and Palaung), rafting trips and elephant trekking can all be organised out of Chiang Dao in the form of one-, two- and three-night trips. While costs are a bit higher than what you may pay in Chiang Mai, this is a far less-trekked area. Chiang Dao is also convenient to two large national parks, with Chiang Dao National Park being particularly noteworthy. Excellent accommodation is available in Chiang Dao.
Midway between Pai and Mae Hong Son, the blip of a village Soppong is best known for the nearby Lot Cave -- a massive cavern, a part of which you can raft through. A largely Sham area, the entire district is riddled with caves and trails and many people opt to do a series of short day walks out from here rather than longer multi-day treks -- though the latter are also possible. Easily the best source of information is the long-running Cave Lodge, which runs all manner of trips and excursions -- and is also just a great place to hang out. This is a good option if you want to see a bit of Thai wilderness but find the whole "hilltribe trekking scene" a bit jading. The neighbouring traveller hot-spots of Pai and Mae Hong Son each have their own heaving trekking scenes.
Right at the other end of the spectrum, there's a totally different flavour of trekking available out of the least Thai town in Thailand, Mae Salong. Pony trekking is the speciality here, with trips available to outlying Yao villages. More traditional trekking, mostly to Akha, Hmong and Shan villages, is also available should you not be wanting to inflict your weight on a pony. Mae Salong was one of the towns the KMT nationalists escaped to from China and it retains to this day an overpowering Chinese vibe -- the tea is excellent too. While the scenery isn't as tremendous as at some of the other locations, it still is pleasant -- and interesting nevertheless.
Set in the southern reaches of northern Thailand, Kamphaeng Phet is best known for its ancient ruins -- similar to those that can be found in Ayutthaya and Sukhothai -- though don't be surprised if you're the only farang in town. That said, courtesy of the sole guesthouse in town, Three J Guesthouse, there's some trekking potential -- sort of. They've set up a small homestay about 40km west of town near Khlong Lan National Park. From there there's minority villages within a few kilometres' walk, and, well, it's just a really pretty spot!
Last but not least, one of our all-time favourite spots in Thailand, is Sangkhlaburi. Set out near the Burmese border in the far western reaches of Kanchanaburi province, Sangkhlaburi has tremendous potential with a bunch of national parks, waterfalls, lake and boat trips, rafting, elephant riding and minority villages (predominantly Mon and Karen). Many of these spots can also be visited from Kanchanaburi itself, but Sangkhlaburi is a far nicer place to stay. The scenery is simply stunning and for the truly independent, with a spare bit of cash, there are some pretty amazing trekking options out of here.
So there you go, 10 destinations outside of Chiang Mai that can all be used as a base for trekking. Prices will vary a bit -- generally the smaller the town, the bigger the cost -- but this is a business in which you get what you pay for. Once you've settled on where you want to trek, take a look at our general advisory on trekking in Thailand, which contains some useful pointers for both keeping your expectations in check and for finding the right trek for you.
Stuart McDonald co-founded Travelfish.org with Samantha Brown in 2004. He has lived in Thailand, Cambodia and Indonesia, where he worked as an under-paid, under-skilled language teacher, an embassy staffer, a newspaper web-site developer, freelancing and various other stuff. His favourite read is The Art of Travel by Alain de Botton.