I loved Chiang Rai. We stayed two nights and it was not long enough to explore. It is the smaller sister-city to Chiang Mai and I much preferred Chiang Rai.
At the Night Market I found more high quality and unique goods. I ended up buying the bulk of my souvenirs and amazing decor for my house here. Everything from silks, trinkets, jewelry, wooden Buddhas, elephants, and more were a much higher quality that what we saw in Chiang Mai.
There were some amazing things in Chiang Rai:

The White Temple

Tea Plantation

Cat Cafe

Hill Tribe Villages

Hot Springs

Night Market with drop dead gorgeous amateur lady boys

Anthony Bourdain restaurant with one of the best steaks you’ll ever eat

Our hotel had one of the most unique 3-headed Naga I have seen

Mango Sticky Rice