I was up at Maeshowe on holiday this summer, and what they're doing up there is trying to turn the place into a tourist attraction on the lines of the Newgrange Tomb complex in Ireland. To get in, you have to book on a tour, and go up to the tomb with a guide who will then proceed to lead you up there, talk a load of old toot at you, then boot you out of the place again in no short order. Personal photography is completely banned, partly to preserve the Scottish Tourist Board's monopoly on images, and partly because getting decent shots of the various inscriptions would take quite a bit of fiddling about with tripods, carefully-positioned point-light sources and long exposures.
And of course, doing this would seriously disrupt their carefully-scheduled shuttling of tourists through the monument.
As I remember it, nowhere else on Orkney does this. The Ring of Brodgar is completely open, are are the Stones of Stenness and all associated monuments. Skara Brae is now a "Look from the path, you cannot go into it" job, though, with extremely serious-looking English Heritage bouncers in attendance at all times. The Tomb of the Eagles is well worth a visit, if only for a truly stunning walk over from the visitors' centre (and farm) to the actual tomb; I'd advise taking knee pads for getting into the tomb though, as the "lie on your back on a skateboard" routine only very vaguely works.
Wideford Tomb is completely open, though taking your own torch is a good idea since the old industrial-grade torches have been replaced by poxy little LED wind-up jobbies.
Finally, you'll likely see a whisky called "Scapa Flow" being sold up there. Avoid buying any; industrial ethanol is cheaper and about as well flavoured.