Phetchaburi is a lovely small town in central Thailand. It's not a big place but it is a bit spread out so having some sort of transport is handy. Plus, in the case of Phetchaburi, not having to walk also means avoiding a whole lot of monkeys...
As is typical of south east Asia, the most convenient and most readily available form of transport is a small motorcycle. There are millions off them around and they typically outnumber cars on the road by a healthy margin. They are reliable (usually), cheap to run and perfect for zipping around town.
While a motorcycle is convenient remember that riding a motorcycle comes with a set of inherent risks. The people renting motorcycles to tourists typically don't care if you know what you're doing but you should not assume that you can magically ride a motorcycle just because you are on holiday.
Enough doom and gloom, here is a little video we made while we were out exploring Phetchaburi. I've now spent a lot of time on a bike in a variety of locations around south east Asia. The traffic was expected. The monkeys on the road were a bit of a surprise.