I like the 80s soul/funk/pop route (Prince, Michael Jackson, Stevie Wonder, The Cure), but that's just my personal preference. That's the thing about weddings, you can't please everyone! Have a variety of styles but most of all go with what YOU love - happy bride and groom = happy guests.
You know how entrenched your guests are likely to be!
But I'd go for a lot of late 80s - the stuff people will all know and remember and think fondly of their (wild) youth.
Transvision Vamp, Queen, FGTH, Soul2Soul, Springsteen, Pet Shop Boys, Fine Young Cannibals, Dead or Alive, Divine, Redskins, Doctor and the Medics, the Communards, Nina Simone, Bon Jovi, Blondie, Detroit Spinners, Adam and the Ants, Kellie Marie, Wham!, Soft Cell, Human League, Depeche Mode, The Jam, Eddie Grant, Bonnie Tyler, Duran Duran, Madonna, Yazz, T'Pau, The Bangles, Kylie, The Timelords, Pepsi and Shirley, Belinda Carlisle.
I agree ask your guests for request lists! My mate also chose songs that were relevant to each group of friends during her life time, from school discos to college parties, so each person felt a special bond and had a special little dance with the bride and groom!