General travel information on Thailand northern provinces is available
on a Gopher server at Chiangmai University's gopher server.
  gopher://gopher.chiangmai.ac.th/11/.TOURISM

Webmaster@infothai.com has suggested on December 20, 1996, that travel
information related to Chiang Mai and Chiang Rai areas can be found at
  http://www.infothai.com/wtcmcr/

From: ssg9328@uxa.cso.uiuc.edu (Samart Srijumnong)
Date: 12 Jan 1994 01:47:13 GMT

First of all, one weekend would not be enough for hill tribe village tour. 
The shortest trek tour takes four days. Chiangmai and other areas close
by along should comfortably fill the whole two-day/two-night trip. As MBA
students, they may want to look for some "selling points" from the things
they see, e.g. local arts, tourist attractions, people's attitude and tastes.
If this is the case, it would not matter much where they go anyway.

Concerning the place to stay, here are the places listed by Joe Cummings,
in his tourist guide...THAILAND, (1990), under "top end" category. 

Chiang Inn Hotel, downtown, from 920B
Chiang Mai Hill, 18 Huay Kaew Rd., from 726B
Chiang Mai Orchid, 100 Huay Kaew Rd., from 1210B
Chiang Mai Plaza, 92 Si Donchai Rd., from 950B
Chiang Mai President, 226 Vitchyanon Rd., from 847B
Dusit Inn, downtown, from 1000B
Poy Luang, 146 Superhighway, from 886
Rincome Hotel, 301 Huay Kaew, from 1331B
Suriwong Hotel, downtown, from 1089B

The followings have some rooms with airconditioning (middle class?)

Anodart Hotel, Ratchamankha Rd.,  280-480B
Bualuang Hotel, 16 Huay Kaew Rd., from 350B
Chang Phuak Hotel, 133 Chotana Rd., 250-400B
Chiang COme Hotel, 7/35 Suthep Rd., 300-500B
CHiang Mai Phucome, 21 Huay Kaew Rd., 550-880B
Diamond Hotel, 33/10 Charoen Prathed Rd., 400-930B
Iyara Hotel, 126 Chotana Rd., 450-550B
Little Duck Hotel, 99/9 Huay Kaew Rd., 400-500B
Muang Mai Hotel, 502 Huay Kaew Rd, from 420-480B
Nantana Pension, 72/76 Tipanet Rd., 250-350B
New Asia Hotel, 55 Rachwong Rd., 220-1200B

I also mentioned YMCA in other posting. The price is quite reasonable there.
I have not given the phone as you may only want to use the number to estimate
the trip cost. When you are in Bangkok, you can acquire their number and
contact them. To book room for big group like this should get some discount
which sometime up to 50%.