If Darth Vader could find a tux to fit over his massive breathing apparatus, this would clearly be his first choice of neckwear.
R2-D2 looks so dapper in his bowtie! He'd make a fantastic ring bearer. I bet he's got a little compartment in his head there that he could store the rings in. I guess he makes a good cake too, but I'd love to see a whole bunch of these guys cruising around serving drinks at the reception.