An excellent to visit is the hot spring of Pong Phrabat. You could do some walking in the nearby national park of the same name. Take highway 1 north out of Chiang Rai, to the first village (Bandu) / turn off, past the airport. Take the access road along the highway and turn to your left, drive up this road for a km or so until you have a sharp right hand turn. Instead drive through the gate straight ahead of you with the pond on your left. For the Pong Phrabat waterfall just continue on the paved road for another 5 km's until you come to the end parking. From there it's a 20 minute walk. No entrance fee required!
At this point you are about 500 metres from Mon Far Mountain Resort.