I can do either or, but normally in the summer I will wear only shorts and in the winter I do perfer the pants. But the pants I wear are not heavy material so it isn't the much more and doesn't cause me to get too hot. I wear Nike Dry fit and LOVE LOVE LOVE them!!! I actually have to wear pants for certain workouts wear I know I have to hold the medicine ball in between my legs, because with shorts my legs get to sweaty and the ball will slip out and land right on my ad area... ouch!
There are workout pants out there that are of heavy material that I couldnt' workout in even during the winter, but Nike Dry Fit is just great! They look great, they feel great and well gosh darn it they are just wonderful.