In lieu of towel rings, simple hooks are also a good idea. (potterybarn.com)
A sleek brushed bronze towel ring placed between the double vanity mirrors offers an attractive way to air dry and keep a hand towel close by both sinks. (hgtv.com)
And some new towel rings (2 - one at regular height, and one down lower for my kiddos). (theinspiredroom.net)