Rental car for northern trip

[Dcheech]

Any recommendations on Rental car company, and car to rent. I need to do a loop trip with the G Friend: Chiang Mai,  Phayao, Phrae, then return. The trip will be three days or four days. I have driven in Thailand before. I'm licensed,  and the girlfriend is a licensed and qualified driver..

 

Planning on renting in Chiang Mai. Many companies seem to have offices at the airport. I'm in town, and likely would use Avis, only because I have rented with them before. Any comments, things to look for, insurance coverage to buy or NOT to buy, Potential scams. Hope to do this next week. It is family business but going to make a trip out of it.

 

Thanks for any and all advice and recommendations.