Having been travelling all my life, and mostly long time in Thailand (my answer is here actually), i would say simply :
+ Business, daily business like renting a condo, a scooter, buying a transport ticket, food, massages, shopping, etc. Thailand is imo by FAR the No 1 in the world ! Like it's on another planet. Everything works well, good price, excellent service, trust, easyness, quality, politness !
And i mean by far. Compared to any country in Europe, USA, and hmm of course Latin America, Africa, India, but too Philipine, Laos, Cambogia, Vietnam, etc.
+ People. No argument, always polite (with very few exception in overtouristic area), easy to live by, funny.
+- : not many are strong intellectually and culturally suited, but to be nice is more important.
+ People are beautiful (and let's say "slim" to not offense the others ????) especially in the north. And let's say it : girls are much more "cool" than in many other countries.
+ Buddhism ! It's a philosophy, a way of life, source of many of those positives (but curiously it's not the case in India as i remember - 20 years ago that's said)
+ Safety.
+- Climate : the BIG problem is pollution. The high season is actually the smoky season, even in the south.
At least it's not cold, there are some nice beachs, mountains, the Mekong, etc.
+- Government/immigration policy : opposite to "before", it has become very complicated, and not nice sometimes. Hope it will change for the best, not only for Chineese/Indian tourist-pack, but for high or medium networth tourists/travellers/expats too. Waiting for that.
- Driving ha ha ! Not a big issue for me, but wow !...
Being in Mexico now since 6 months (with 2 in Colombia), i can say i really can't wait to come back in Thailand !!!!!!
But i may have to wait actually, some clarification about the entry soooo-many conditions still affecting maybe the strongest force of Thailand, it's hospitality (but i mean business too ???? ).