I'm going to keep this simple. I don't need to tell you why Chiang Mai has been one of my favorite places in Thailand--I can show you.
I did a temple day, in which I walked around, sweating in my long pants and sleeves (make sure you cover shoulders and knees for visiting temples, it's basic respect), stopping at whatever temples caught my fancy. I was lucky because most were still decorated from Songkran the water festival in Thailand. I would definitely recommend you hit a few of the big ones.
One of the biggest and most popular temples, this one was quite nice to walk around. Known for its huge chedi, which was built by a king to contain the ashes of his father, it's massive structure will amaze. I particularly enjoyed the monk chat, where you can ask the monks questions and talk with them. I learned that while women do not become monks anymore, they can become bhikkhunis which is similar to a Buddhist nun. You will see my pictures of these women and girls swathed in white from Wat Phra That Doi Suthep.
Phra That Doi Suthep
Known as the temple on the mountain, you must take a taxi or scooter from the old city (inside the walls) of Chiang Mai. You can find a song-taew or red truck that fills with tourists and backpackers heading all for the temple and only pay about 100 thb roundtrip per person. Just ask your accomodation where the nearest pickup for Doi Suthep is. The trip is totally worth it, however you do not need a ton of time here; an hour is enough to see everything. Climb the Naga Staircase to the top. This is where a sacred white elephant carrying the Buddha's shoulder bone was said to have stopped, thus blessing the area. The temple glistens, the golden fixtures blinding. Come around 2:30 and you might see the monks and nuns chanting, as I was lucky enough to experience. And before you go make sure you visit the look-out to see a beautiful view of the city.
Another very popular temple, known simply for being old and notable and large. I enjoyed the temple itself less than many of the others I visited, but the grounds and smaller buildings were nice. Be prepared for many golden Buddhas.
Don't skip the small ones. Don't stop at every temple either as you won't survive the day. It is best to peer in and see if it strikes your interest. That is how I found a new temple, the walls being painted by a monk. Or Wat Lok Molee with its pretty little garden and lack of tourists. I found I prefered to stop and sit in front of a Buddha in some of these quiet, little temples rather than where you all you hear is tourist chatter and the click of cameras.
The bazaar has more clothing and brand goods than the Sunday market. Come here if you need a new backpack or a sturdy pair of shoes. There are plenty of food stalls and restaurants and even some entertainment.
Sunday Walking Market
This market is not to be missed! Try to come to Chiang Mai for a Sunday evening, as I came to this market twice and loved it. You will find everything from vintage dresses to painted lanterns to leather goods. I found many of the goods here to look actually handmade and a higher quality than most markets. Perfect for finding presents or a little something for yourself. And don't bother getting dinner before you go! There are many pockets and squares filled with stalls selling the tastiest and cheapest food. Try the soft-boiled quail eggs or the gyoza dumplings and finish with the traditional favorite--mango sticky rice!
Get a massage.
This is something you can do anywhere for cheap across Asia. And it could possibly be very good. Possibly. That is why I recommend you do it in Chiang Mai. There are a few locations that offer massages from ex-convicts who are rehabilitated. I went to one of these (near Chang Puak gate) and had a positively delightful thai massage for 180 thb. So worth it.
Find a local artist or goods shop.
Browse about, as I did in HQ Paper. They sell beautiful, handmade paper that is manufactured right outside Chiang Mai. I don't know how, but I found a place in my suitcase for a roll of the stuff.
Explore the cafe culture.
This is something especially close to my heart, as I have a true fondness for a good cappuccino in a funky, local joint. Into the Woods had a cutesy vibe and good wifi, but the coffee across the street at the tiny espresso bar (I forgot the name!) was stellar. Fresh & Wraps by the east gate was easily the best aand freshest meal I had in a while.
Walk the moat.
There is so much happening around the moat and the gates: street food, markets, and good restaurants. The added plus is the scenery of the water and the rush of traffic.