I wear spandex/lycra/cycling-specific clothes 100% of the time. I don't understand the angst on this forum regarding lycra. I've been wearing cycling-specific clothes since the early 1980s. First time I tried chamois shorts (wool back then), I was hooked. First time I tried a synthetic cycling jersey, I never looked back.
My commute is 22 miles round trip on hilly roads. If I had to ride that far every day wearing regular street clothes, I would be miserable and probably suffer from a chronic case of saddle sores. My jerseys are all in very bright colors, so that makes me more visible and safer riding in traffic as well.