Chiang Rai downtown is about 30 minutes away from the airport. Taxi fare is about 400 baht. The taxi which is non-air conditioned can accommodate about 6 to 8 passengers depending on the amount of luggage. It's sort of difficult to recognize the taxi as they don't have a taxi signage. Their taxi is actually a van and it is advisable that we check the price first before boarding one. However, I noticed that most of the people in Chiang Rai are friendly as it is just a small town.
It is easy to move around within the town of Chiang Rai as most of the tourist spot within the town are quite near to each other. There are sign boards everywhere showing the location and the distance. And best of all, there are restaurants everywhere. And food in Chiang Rai are reasonably priced.
It was in May when I was in Chiang Rai. The weather was quite hot even during the night. I was told that the best time to visit Northern Thailand is during November to January as the weather will be cooler.
Actually what I enjoy most of Northern Thailand is the scenery and food.