I have yet another question for you experts!

I am getting work done to my bike, and one of the things I want to change is the pedals. Right now,they're just regular, non-clip, flat pedals, and I hate them. I know that I will need clipless pedals soon, since I'm training to ride a century, but I am unsure if I will need to have a non-clipless set for my commute. I have a lot of stops and starts on my route, and I often end up in at least a bit of traffic, so that's my main concern. I do see commuters riding clipless, but I'm still unsure.

Do any of you do your commute in clipless pedals? Do you deal with traffic?

Thank you again for all of your help to this clueless newbie!