All major international car rental companies, such as AVIS, Budget, and Hertz, as well as Thai car rental companies, have various vehicles for rent and are ready to provide suggestions on travel itineraries. Most rental agencies can be found at the airport.
Be aware that only Commercial First Class Insurance provides full coverage on rental cars, opposed to limited personal or third party insurance.
Most international car rental agencies will offer this insurance (some only for those with a valid international driver’s license) while local companies may or may not. You may wish to request a copy of their insurance policy and ensure that it states “For Commercial Use”. Regardless, inspect rental vehicles prior to rent and drive with caution as traffic in Thailand can be quite confusing, especially the habit of Thai motorcycle drivers as they often drive on the wrong side of the road.