If you visit Arran take the ferry to Claonaig and drive up to Kilmartin. Kilmartin Glen is an area with one of the richest concentrations of prehistoric monuments and historical sites in Scotland. It contains over 800 monuments within a 6 mile radius including standing stones, chambered cairns, and the Royal fortress of Dalriada which includes a stone footprint, thought to be part of the coronation ritual.

I would second the suggestion of the Kelpies - easy access and very impressive.

Andy

Certainly the Kelpies. Fabulous! Not sure how to add a photo - but I took a lovely one there last year. Can anyone help with how to do it, I would love to share?

I've googled them, they look amazing. Thank you for all your suggestions, and for the emails I've got! Now for the tricky part to find lodging!

If you do go to Arran, I really seriously recommend The Glenartney in Brodick. It is a small place run by a very, very friendly young couple. The rooms are on the small side but very clean and comfortable. The breakfast is fit for champions.
Ross the owner is a member of the local Mountain Rescue Team and every afternoon hsi wife Hannah bakes cakes for the guests, they are free but a donation to the MRT is expected. They have a great drying room for guests to leave wet kit overnight (also used as a store for the MRT kit) They don't do evening meals but if you bring in a takeaway from the Chinese down the road they provide plates, glasses etc. for you to use in the dining room.

For any doggies visiting it is a real treat, pooches receive a welcome pack which includes a towel for getting rubbed down when returning from fun outdoors, some treats and most importantly a sausage voucher which entitles them to a breakfast sausage every morning.

https://www.tripadvisor.co.uk/Hotel_Review-g551754-d610935-Reviews-The_Glenartney-Brodick_Isle_of_Arran_Scotland.html

http://http://glenartney-arran.co.uk/

There are bigger places but I challenge anyone to find anywhere more comfortable or friendly.

The Kelpies:

Not sure if this will work, as I have just discovered Flickr today.

Try this to see the magnificent Kelpies
https://www.flickr.com/photos/159715383@N04/albums/72157691966956361

The Fife fishing villages (St Monans, Pittenweem, Crail) are delightful and just over an hour from Edinburgh by car. You can then go over the hill to St Andrews for historical stuff (it's not all golf). Easy walks along the beach there.

Glen Coe is touristy but very dramatic with walks at all level of difficulty - roughly 3 hours from Edinburgh. Fort William is a bit of a dump (IMO) but the road to Mallaig is superb. Arisaig and Morar have fantastic views to the isles with good boat trips to Eigg, Rhum and Skye. I'd recommend the Old Library B&B in Arisaig.

Further north, out of the Challenge area, Sutherland and Assynt are superb but it means a lot more driving.

South east of Edinburgh there are some great low level coastal walks. St Abbs Head near Coldingham/Eyemouth. Berwickshire Coastal Path: Berwick upon Tweed to Cockburnspath,you can get a bus and walk part of it.
Various walks around Dunbar and North Berwick or head inland to the historic Border towns of Duns, Melrose, Peebles etc.