If they were to go with a Queen song (other than Flash) then I would say Killer Queen. I reckon they could whip up a pretty quirky version... although... it is already!
Other possibilities:
-Eye of the Tiger... why? Cause it's a ripper of a song and I'd love any of my favourite bands to have a crack!
-Tainted Love... might as well... every other band has covered it...mwuhahaha
-Wake Me Up Before you Go go... actually, no... not the song... they could just remake the clip..
I like the can't take my eyes off you cover... cause it's a song you wouldn't really pick them to do... I'd like them to do another cover like that... hence the wake me up suggestion... mwuahahahhahaaha.
Actually... on a serious suggestion... I'd like them to do something by Smashing Pumpkins.. although, I don't really know how they would alter the songs as much! But I think something like 'Forgive' as a slower song and maybe Cherub Rock as a heavier song would be kinda cool.