Be sure to bring a guide book with you. Either Fodors or I like Eyewitness. They are more expensive but have much better street maps.
There are a lot of temples.. some are big..and some you will find as you are just walking around and they sometimes are the most interesing. Pick 3 or 4 from your book and then any you may see on the way.
Main ones are Wat Chedi Luang and Wat Suan Dok.
Also regarding the Elephant camps if you don't have a pesky taxi driver, just check at the hotel they can advise you of the best tours.