Had a wonderful weekend on the bike in Donegal. Thought I'd recommend a route for you in case you're ever out this direction. Only a little of this route is on the Wild Atlantic Way, but if you are doing the WAW, I'd strongly recommend you make time for this slight detour.
I travelled from east to west. This route starts to get wild and beautiful near Termon, outside of which, on the left-hand side of the road, is a sword in a stone - so you can have a quick check to see if you're the True King Of Ireland or not...
From there it gets more remote, as you go past Glenveagh National Park, the trees fall away revealing a rocky landscape, then the looming mountains, first of Muckish, then Errigal appearing on your right. The road is wide with fast sweeping bends, great visibility and a good surface, but as you get to the car park for folks climbing Errigal, you'd be wise to slow down as there's usually lots of cars parked on the roadside and people on foot. As the road ducks around Errigal it sweeps down into the Poisoned Glen, with amazing views of Dunlewey on your left and Errigal a constant presence on your right. The road here isn't as well surfaced, but the views more than make up for it.
As the road rolls down from the mountain towards the Atlantic, it joins with the N56, and you'll follow a great road with a lovely surface thought the villages of Gweedore, Crolly and Loughanure, alongside a meandering stream through rocky hills and boggy lakes. It's twisty heaven, with plenty of elevation changes, lovely scenery and flowing lines. From Loughanure it becomes less twisty, but faster flowing lines on a great surface make it ideal for sports bikes. We stayed close to Dungloe (also known as Dunglow, or An Clochán Liath in Irish), so I can't really comment on how the rest of the WAW is, but this 60 odd miles is a spectacularly good ride.