Non-denim shorts can be a step up for longer rides. A lot of denim is pretty damn thick. Bike shorts stay dryer for the most part. Jeans are a lot easier to ride in when it's 55 degrees than when it's 85 degrees. I ride in board shorts quite a bit. They can get a little clammy but have slimmer seams than jeans and dry out quicker.

I've even done a century in a pair of Rip Curl board shorts. I'd hate to do one in the heat with Levi's and Fruit of the Looms, though.

Wrangler Hero shorts are pretty good for 50 mile rides or less. Slim seams and fairly thin material. I wear them over bike shorts often when it's less than 75 degrees out.

I've found that padding in bike shorts is generally too excessive for my tastes but the other benefits outweigh that negative.