Not long after we got married, the missus bought a micra. It was the 3 doors version and we thought it was right choice, as it was only for us 2. However, we regretted our decision soon after because, on the 3 doors, the doors are much longer than the 5 doors, making opening doors in carparks with narrow spaces very difficult. You have to open them that much wider to get out.
5 doors might not look as smart as the 3 doors, but as Martin and mike said, it gives you better option and resale value.