Is it safe to get a driver in Thailand for a girl traveling alone? Like for a 2 to 3 hour drive outside of Bangkok...?

I think it is not the good choice. A driver is like a taxi? I'm a Thai studying in Bangkok. I don't think it will be safe. If you are interested going outside of Bangkok, I recommend Ayutthaya. When you are in Bangkok, you can go to there by a train at the Bangkok railway station, HuaLamPhong. It takes time about 2-3 hours from Bangkok. You will be impressed.

You have to be careful. Yes most drivers are safe but their have been a few cases where a taxi driver has raped either a tourist or local Thai woman here. It is best to get a driver from a tour agency if that is what you want. But if you decide to go with a driver you don't know much about take a photo with your photo of the license plate numbers and his ID card which should be in the sun visor also a picture of the driver.

Sounds risky...better not. If you want to go outside of Bangkok, join a tour group. Or at least travel with a few friends.

Hiring a taxi driver is a roll of the dice, you get what you get and who knows. To be safe? It may cost you double what you may expect is hire a car and driver from the Hotel, the driver works for the hotel. They will be on call for you for the time you hire the car and driver. There are car services that drive to certain cities around Thailand for a price. Truthfully, your best and safest is to hire a driver and car from the hotel if they offer this.

Yes

If you are careful. Here's the details of a company which uses lady taxi drivers: http://www.namstaxipattaya.com/

i wouldnt risk it

You can bang my kok ;-)