While Southern Thailand can be somewhat polarizing (people either love the beaches and parties or feel scammed by the locals and overwhelmed by the crowds), most people I met while traveling fell in love with Northern Thailand. I didn't really have expectations for Chiang Mai or Pai (again, having no expectations is key) and I fell in love with both cities.
First of all, buy this map of Chiang Mai. My friend Naseem and I bought it on our first morning and discovered everything from tiny used bookstores to a lavish afternoon tea party at a swanky resort. We stayed at Hug Hostel, which I would highly recommend. It's that incredibly rare combination of clean and social, with a big, comfortable rec room for reading and lounging, and a bar downstairs with ping pong and unbeatable happy hour. The food in Chiang Mai is incredible -- I ate almost exclusively from street carts and never had a bad meal. We splurged on Western breakfast one morning here and believe it or not, the Eggs Benedict was just like at home.
In terms of activities in Chiang Mai, we rented a motorbike and drove out of town along the Mae Sa Loop (pro tip: the "waterfall" stop is not worth it at all) which was beautiful and so, so relaxing. There isn't one "must see," but it's pretty unique to drive along a road where you frequently see elephant crossing signs.
So that brings me to....elephants. Animal tourism is a hot topic of conversation in hostels in Thailand. The overwhelming response by people who have done their research is that tigers are never okay. So next time you see the notorious Tinder profile picture of the dude with the tiger...swipe left. The tigers are always heavily drugged...I mean seriously, they're TIGERS. They don't want to cuddle with humans.
Elephant tourism elicits mixed reactions. I did quite a bit of research and found an elephant farm, and while there I felt very comfortable and happy with my decision. We fed and bathed the elephants, learned about their care, and briefly rode them bare-backed without the basket that leaves cuts in the animals' backs. Another thing to look for when seeking a humane option is whether or not the animals perform. There were no elephants playing soccer for our entertainment at Patara. This day-long experience was a big splurge (I paid about $200), but when food and lodging are costing you $15/day and you can feel comfortable about the animal treatment, it's well worth the cost.
As with most activities you sign up for through hostels (and this was my experience everywhere), the company picks you up and drops you off at your hostel. On the way back from the elephant farm, our guide/driver/elephant trainer extraordinaire asked me if I wanted to go see some Chiang Mai soccer at the local stadium. My knee-jerk reaction was "no" but I quickly realized that opportunities like this are kind of the point of traveling.
I grabbed a friend from the hostel, met our new friend at the stadium, and enjoyed $3 tickets, $1 beers, a rowdy Thai crowd, and a Chiang Mai victory. I'm happy this experience happened early on because it set the tone for a lot of yes-saying...which resulted in a truly unforgettable adventure.