Look for a bag with external compression straps...my wife is currently traveling with an eBags TLS Mother Lode Weekender Convertible Junior (whew!) and she is strapping the yoga mat on one side using the external compression straps. She is using a travel yoga mat though, which is thinner than your regular yoga mat. Note, the travel yoga mats are thinner and can actually be folded square...so if you clear enough room in your luggage you could pack it with everything else.
Last edited by aabrock2187; Apr 24, 2014 at 3:23 am
Reason: more info on travel yoga mat