I am pondering whether to buy a XL courier or not as I have a couple of International work trips coming up.... I looked through pics and it is MASSIVE looking when worn. I was wondering if it would make a good carry on or is it too big, bigger than allowed by airplane rules? I will also be carrying my instrument which is large. My other option is the weekender. What should I get? Also, it is indeed not flashy as to attract unwanted attention, right? (Spain and Mexico are our destinations) Or should I carry a canvas bag from Target? Thanks!