I have worked up that way for a few years and I'm familiar with Lerwick in the Shetlands. Mostly visited by Norwegian yachts, but some Brits too. The main town of Lerwick has much to offer, full provisioning, yachts services, fuel and most importantly, Capt. Flints Bar.
The 'marina' is a protected inlet open from the North or South, and is situated virtually right down-town. The Airport in Sumbrugh is about 20 miles away, right at the Southern tip of the Shetlands. Taxi's a 'plenty.
I'd say you would appreciate the stop. If I'm sailing that way anyday, I plan to make a stop in Lerwick. I hear the other surrounding bays are quite nice too. That whole area is pristine, I imagine just as the Vikings saw it.
Never really pulled into the Orkneys, so cannot adivise.