Historic Sites – paid attraction visitor passes
There are two big organisations : Historic Scotland (HS) and National Trust for Scotland (NTS). They each do their own pass/membership – and there is a combined tourist pass for these.
In addition some privately owned attractions belong to the Historic Houses Association and their Friends scheme offers free access to some – but not all of these properties.
Check out which each place you want to visit belongs to (if any) to decide what is best value. The Google Map gives the 2016 Adult single visitor cost for each paid attraction.
Typical charges per attraction is in the £5-12 range for an full price adult ticket. The most expensive are Edinburgh Castle at £16.50 for an adult with Stirling is a bit cheaper at £14.50 (HS). Concessions apply to children, students and Seniors (over 60s).
As the tourist pass for 7 days out of 14 is about the same as the annual membership, visitors for longer periods or who visit a major HS or NTS attraction each day might find joining advantageous.
Also if you already belong to your own countries big historic charity, check whether you have reciprocal rights anyway with the National Trust for Scotland. You might find you get in free! It might be worth joining your local organisation before you arrive here. I have heard reports of some ticket offices for NTS properties not being aware of the reciprocal deal, so print out the page and bring it with you. http://www.nts.org.uk/Site/Membership/Reciprocal-entry-sites/
National Trust for Scotland (60+ paid attractions)
Membership up to £54 for an adult with no concessions or discounts. £60 for two people (if one is over 60) https://www.nts.org.uk/Membership/Monthly/
National Trust Explorer Pass 3 days from 7, 7 days from 14 at £31.50 or 14 from 30 days options. https://www.visitbritainshop.com/world/national-trust-for-scotland-discover-ticket/
There is a decent distribution across mainland Scotland with the exception of Caithness and Sutherland. The maps of key NTS attractions is here:
Historic Scotland (77 paid attractions).
Membership £69 for a couple where one is over 60. £49.50 one adult. https://members.historic-scotland.gov.uk
HS also do Regional passes so if you are focusing on one area, have a look at https://www.historicenvironment.scot/visit-a-place/explorer-passes/#section-3 They last for 30 days.
HS Explorer pass Fairly tight time windows – might you be as well just taking an annual membership? https://www.historicenvironment.scot/visit-a-place/explorer-passes/#section-2 £30 adult 3 out of 5 days. £40 adult 7 out of 14 days.
Be aware that there is only one (Urquhart Castle) mainland Historic Scotland paid for attraction north west of the Great Glen. The full map of attractions is in this brochure
Joint Historic Scotland/National Trust Pass
Historic Houses Association (32 properties in Scotland)
There are 32 HHA properties in Scotland including Dunnotar Castle, Dunrobin Castle and Dunvegan Castle
Membership costs £48 for a year and covers properties in England and Wales as well as Scotland.