There's a thread in the commuting forum called "How do you carry a pizza?" I'm a little less ambitious ... but I'm asking in this forum, because chances are most people in here have a similar bike to mine ( drop handle bars, skinny tires, etc ), and do the same kinds of riding I do ( 90 % on pavement, with love for a good dirt trail and/or stairs now and then ), so it seems like I'll get better answers here.
I don't like riding with a backpack. It prevents me from managing my body temperature; I wind up sweating more, feeling hot and clammy, etc. I prefer hiking without a pack, too... Anyway, I've never used panniers, but have a bit of nervousness about them. I've got a small bag attached to the bottom of my seat, and keep some tire levers, a multi-tool, dental floss, etc, down there. When I hit a bump in the road, the thing knocks the saddle, and I always wonder for a split second if something has come loose. It seems like panniers would be more of the same, but also ( more importantly ) change the way the bike rides. And I really like the way it handles now.
So, a bike is one of the most fun things I've discovered in life, but it's also transportation. Sometimes I just want to go to the park ( which might be a mile away, or ten ) and enjoy some time outdoors with a good book. Ideally I'd also like to be able to carry a meal, and a jacket. Same goes for visiting friends across town ... it's pretty often I'll want to bring a book in at least one direction.
What do you do to move your stuff around? How does it work for you, and would you recommend it?