Ooh, good thread. I'm a bit rubbish about knowing who sings what etc but like most people on here (I suspect) I know what I'd like to dance to if I was on SCD.
I also agree with Len a bit that some dances suit older songs better.
Top choice has to be 'Moonlight Serenade' (Glenn Miller Band) for a foxtrot, or maybe 'Bewitched, Bothered and Bewildered' (Sinatra?).
Also they're cheese on toast (as someone said earlier about Brendan

) but 'I Think I'd Better Leave right Now' (Will Young), 'Somewhere Over The Rainbow' (Eva Cassidy) or 'Closest Thing To Crazy' (Katie Melua) could work well for rumbas.
Jive seems relatively easy to pick for with 'Boogiewoogie Bugle Boy', 'I'm So Excited' (Pointer Sisters) and 'Making Your Mind Up' (Bucks Fizz) my favourites because I think all would lend themselves to memorable choreography.
I'd also like to see 'Paint It Black' (Stones) for a paso and 'In Trutina' (as used by Torvill & Dean) for an Argentine tango. And I think we could all imagine Ola cha cha-ing to 'Sex Bomb' (Tom Jones)
'For Once In My Life' would make a great American smooth (Michael Buble version) or samba (Stevie Wonder version).
Sorry for long post, got a bit carried away!