Greek: formal you is usually used with older people (but not family), teachers when you are a student or higher ups in general. Wherever I've worked we used the informal form but I don't know how common this is. Also retail workers typically use the formal form with customers so I do the same with them but many people do not. It seems to be slowly going away as a feature.

Spanish: I'd use the formal a bit less than in greek but it depends on location. In Spain it seems pretty rare but some central and south American countries use it much more.