I've alway taken a backpack - until this year. Two reasons: I get sore spots where the straps sit on my shoulders/arms/you-know-what-I-mean and also, I get tired of taking it off and putting it back on to grab a camera, autograph book, chapstick, etc.
This year I searched out a shoulder bag that I thought might be more comfortable and convenient to use. After searching the mall and other department stores, I finally found the perfect bag (for me) at Wal-Mart. It is made of a really soft vinyl which did not absorb water on wet rides. It has a small zippered pocket inside the bag (perfect for smaller items) and the bag zips (which relaxed me a bit where the pick-pocketing is concerned). There were a few of these bags to choose from, all featuring Disney characters. My bag is silver with a black outline of Mickey on it. There was also a Tink bag and I think there was a Donald Duck one as well, although I don't remember the bag color of those characters. The bag was VERY comfy on my shoulder the entire week, and compared to a backpack, it was just so much easier to get my stuff out out if. I don't think I'll ever do a backpack again.
As a PP stated, my DH also likes to wear cargo shorts and he likes to stuff the pockets with things he likes to keep track of during the day.