Orkney is fabulous, I love it, so much to explore. I've stayed in different cottages each time - I just googled for Orkney cottages. I drove up. I've done the journey in one go a few times and other times I've stayed in hotels in Falkirk or Inverness. I think the Pentland Ferry is cheaper than the other one that I can't remember the name of. There are several itineraries available on Google but I'd say definitely see Skara Brae, Tomb of the Eagles and the Italian Chapel. If you can go when there's a folk festival on, so much the better!