Mysore is the smaller city, obviously. A slower, kinder, easier place with a mild year around climate. Kind of an old fashioned charming atmosphere, not hip unless you are into yoga. Lots of yoga centers near Mysore. The train to Bangalore, a much more happening and busy place, is convenient and only takes avout 1.5 hours, or maybe 2, if I remember correctly. Chennai is a big bustling city and it does get very hot there. Too hot for me by 10 AM.