Hi there Nigel
Well I am sorry to be the one to break the news but since civilisation came to Chiang Mai a few years ago (as long as you stay away from some bars !) and as a consequence, Elephants no longer roam the countryside freely.
There are a few places where you can see them being grazed in sanctuary type environments, some hospitals that are dealing with ex-log workers that have had their, or their babies feet blown off by land mines and some places that put on shows of painting with trunks and displays of up close foot control.
Take your pick.
About the road trips, my advice is to keep reading this forum and get yourself a
GT Rider map from various outlets listed here ... and you will not be disappointed.
Ally