My husband and I don't really have a true "our song", but so many songs from the 70's take me back to our days of being young and super-in-love!
I guess the closest thing to "our song" would be Starland Vocal Bands "Afternoon Delight".
Other songs that really take me back would be Tonight's the Night(Rod Stewart), Follow You, Follow Me(Genesis), You Have Your Own Special Ways(Genesis) Baby I Love Your Way(Peter Frampton)...anything by Genesis, Rod Stewart, Supertramp or Peter Frampton, really.