I never ride my bikes without "suiting up" into appropriate bike clothing. Mainly because of the pedals. If I'm going to put on bike shoes there's no point in not putting on bike shorts, jersey etc. Also, I wouldn't ride without a helmet, so between the shoes and the helmet, and gloves etc. I'm pretty much halfway dressed for it anyway.

I generally won't go out for a ride where I don't plan to do at least 30 miles (this doesn't count my commute which is only 15 miles RT.) Once in awhile I'll do a shorter ride in my neighborhood after work to work on hills.