Plan to do a self-guided tour after a few days in Edinburgh in May.
Would love to hear suggestions for unique lodging that we could use a base for a few nights.
Castle hotel/Air B&B that you loved?

In the Borders -- Traquair House! It is the oldest inhabited house in the country. Very worth visiting but staying there is truly special. Only three rooms are rented out and the breakfasts are great. Quite reasonably priced too. Many castle hotels are eye wateringly expensive.

https://www.traquair.co.uk

Far up north Dornoch Castle Hotel has has historic and modern rooms.

https://dornochcastlehotel.com

In Edinburgh many people enjoy the Witchery just below the Castle

https://www.thewitchery.com/?gad_sou...BoCmfQQAvD_BwE

ps: I've stayed at Traquair House (it was a major bucket list item for me) and at Dornoch, I've only dined at the Witchery.

We stayed at five castle hotels in Scotland a few years ago. Favorite was the Torridon. We've actually stayed there twice.
https://www.thetorridon.com/

We also stayed at the Cromlix house
https://www.cromlix.com/

Also Inverlochy castle. Best dining!!
https://www.inverlochycastlehotel.com/

And Pittodrie House
https://www.macdonaldhotels.co.uk/pittodrie-house

Plus Ballathie Castle Hotel
https://www.ballathiehousehotel.com/

My wife's Shutterfly book
https://www.shutterfly.com/share-pro...HARPRDWEBMPREM

Click on the book, then on "full screen"
Stu Dudley

Re Cromlix (just Cromlix not 'house') -- it is owned by Andy Murray so if you are at all tennis-centric it would be a must but it is also a great hotel with wonderful food. You will need to book well in advance because it is insanely popular.

Tripadvisor calls it "House" also. So does Conde Nast. But the Cromlix site itself does not.
https://www.tripadvisor.co.uk/Locati..._Scotland.html

Note
We stayed at Cromlix for 4 nights, and the remaining castle hotels for 3 nights each. We dined at the hotel every night, and never saw the same menu twice. We dine out in France about 30 times each year, and almost always at Michelin recommended restaurants. Almost all the meals we had at these Scotland castle hotels, were as good, if not better than the Michelin 1 star restaurants in France where we've dined.

Stu Dudley

Anything near Glencoe that you'd recommend?

Not exactly a castle - but a great place to stay: Glencoe House https://glencoe-house.com

And not as posh but absolutely glorious location/views: Kinghouse Hotel https://www.kingshousehotel.co.uk