It took about 2-3 hours, and they suggested a stop mid way at ?Ratchaburi?Petchaburi, can't remember name of the town, but there is a summer palace and temple high on a hill there, which you reach by a wonderful funicular rail thing. it was a beautiful place and made it feel like you had done something useful with the day, instead of just travelling from one place to another. Cost about 2000. check out the ken diamond website. Have fun.