Hello Blaise, greetings from Ireland. Derry today actually!
The itinerary is certainly doable, but it does cover a lot of ground and will mean you wont really see much in-depth of Dingle and Donegal (Not a lot of point in going the whole way up to Donegal for one night and then all the way back down to county Clare next day; you'd need two nights in somewhere like Donegal Town, so you could explore around a little on one full day) So maybe drop the night in Mayo.
In my humble opinion, Id overnight in Dingle and not Ennis. For 2 reasons.
- You will have just come off a transatlantic flight and you're going to dive headfirst into a minimum 5 hours of driving to get from Shannon to Dingle and then back to Ennis, plus another 2 hours of sightseeing driving time needed. Thats elite.
- Dingle is way better.
Actually my heart ached for you a little when I read that you would be in Dingle and yet choose to overnight in Ennis.
But of course, its Ireland, you never know - you may have the best experiences of your trip on that night in Ennis.
Personally, I wouldnt take that chance.
Try for the overnight in Galway also, Its mostly a great town, though of the thousands of people I've brought there on Rick Steves tours over the years, only about 50% have thought that. Generally, but not always, it appeals to more of a younger age-profile traveller.
And the ferry into Clare from Tarbert on the awful bumpy roads, a travel myth. The easiest and most comfortable way is to go to Ennis/Clare/Shannon/The cliffs via Adare and Limerick city. I say that as an expert, I have taken both journeys almost 200 times.
Enjoy my beloved Island. Thanks for choosing Ireland as your holiday destination.
le meas/with respect
Rick Steves Ireland tour-guide
Dingle & Derry