I have done a 8.5 mile r/t commute for 2 1/2 years, work clothes (business casual, no jacket/tie).

Morning is mostly downhill. I only really break a sweat on days like today -- 75 degrees and 90% humidity in the morning.

Evening has a big uphill (315 vertical feet). I get sweaty, but I'm going home & don't care. I have to
wash my pants after each wearing, so they have worn out faster. I use ankle straps to keep the pants clean.