Must Have Songs??

So Fh and I are making our own music cds to play at the reception. We need about a hundred songs and have about 60 so far. It will be mostly background music. We love all music and have a range of jazz, blues, indie, rock (but not too hard--it might overwhelm the guests and owners) and some easy listening are there any must have songs that you are playing at you weddings? They could be during dinner, dancing, cake cutting--whatever! We're so open...