I commute in regular clothes. I pack my 3 oz liquids and wear slip on shoes. For me, the comfort of not having to wear a tie, being able to drink in 1st class, not being bugged by passengers, not having to wear/carry my hat is worth the extra 5-10 minutes it takes me to get through security. I do wear business casual clothes, though, just in case I have to take the jumpseat.