We’re just back from a week there. We had excellent weather which made it fantastic. I even had to take my jumper off once.
The archeological sites are very interesting. Stenness, Brodgar, Skara Brae, Unstan chambered cairn. All worth seeing. This is the last year of the Ness of Brodgar dig. If you are in time to visit it you must before they cover it over again and go off to write up their PhDs. Maes Howe was fully booked until December but they reserve a few tickets for each day which you can get if you turn up in person at 9:30.
Stromness and Kirkwall are worth a half day each.
The Italian chapel
Tidal island ‘Brough of Birsay’ is worth a vist. Accessible 2 hours either side of low tide. Combine with visit to tea rooms (booking highly advisable)
Take bikes and vist some other islands as foot passengers. If taking a vehicle then booking is advisable in summer at least.
Hoy is rugged compared to the other islands and Lyness museum and graveyard are good.
Try the fish