Is suonare like to play an instrument, and giocare to play games, pretty much? That's my guess, but maybe I'm completely off on this.
I thought, in Italian, one could say 'la domenica' (or any other article + day of the week) to represent something that happened every week on that day. As in, would 'suoniamo la domenica' mean the same thing?
No. When you are trying to say that something is happening regularly, you have to say: giochiamo DI domenica. That means we play on "every" Sunday. If you say: Io lavoro sabato, that means that you are working on the first Saturday that is coming. On the other hand, if you say: Io lavoro di sabato, that means that you are working ALL the next Saturdays. Did I helped? 'Cause I know how confusing I can be :)
I think that caustica does have a point. While, as you state hazablad 'io lavaro sabato' means just one (the next) Saturday, 'io lavora il sabato' does mean 'I work Saturdays'. The following site http://italian.about.com/library/fare/blfare110a.htm states 'Marco non studia mai la domenica. (Marco never studies on Sundays.)' It is also discussed here http://www.livinglanguage.com/community/discussion/336/days-of-the-week-and-the-article/p1
You can say either - Io lavoro di sabato OR Io lavoro il sabato. Both means that your are working all the next Saturdays. Only - Io lavoro sabato means that you are going to work next Saturday.
The answer, in part, was le dominiche. This is the first time I have encountered the plural of Sunday. Are all the names of the days of the week pluralized like other common nouns?