I would, as a female, strongly advise against the old "banana hammock". I don't think the string waist would provide much staying power when in competition with the suction of a wetsuit. Plus they are really not that attactive, "manhood" all hanging out like that.
On a side note - I did a liveaboard in the Channel Islands for the New Year. Awesome experience but one of the men in the bunk right next to me wore the speedo. It was, almost infallibly, the first thing that I saw each morning when I got up. Not pleasant.