Scotland or Wales for 3 nights

I would look into flying from Dublin to Edinburgh and staying there for 3 nights. Absolutely loved Edinburgh learning about the history and enjoying the beauty in its well laid out city plan. The garden that separate Old Town from New Town should be absolutely splendid in May. Then I would take the train to London to continue the trip. If you decide to fly rather than take the ferry to the UK, check the baggage restrictions carefully. Some of the planes are quite small and the overhead compartments are limited in size. I was shocked at the size of the plane going between the 2 major cities.

I too am coming down on the side for Scotland. Of course, this is the Scotland forum and you might get different answers on the forum for Wales! You could spend three nights in Edinburgh, exploring the city and maybe taking a day trip somewhere if you wanted to go out side the city. Edinburgh has wonderful history--the Castle, the National Museum of Scotland, Holyrood Palace, the Georgian House and Gladstone's Land all offer great ways to see and learn about the history of Scotland. And, if you haven't gotten quite enough session music in Ireland, you can continue to treat yourself at Sandy Bells. :) If you wanted to do a walk in the hills, you could stay local and climb Arthur's Seat, or you could take a train north to Perthshire and do some walks near Dunkeld and Birnam. Yes, you can walk in Birnam Wood! Edinburgh has some great restaurants as well. If you want more history you could catch the train to Stirling and visit that Castle. The setting is as impressive as Edinburgh. You can easily see from the landscape why it is the gateway to the Highlands. They have just restored the Renaissance Palace.

I would fly to Edinburgh and then do trains. You can catch one to London as well.

Pam

As might be expected I would say Scotland, it is a bigger country and a different history. But depending on your interests or itinerary I would not rule out Wales. If you are into medieval history, the Edwardian ring of steel (Caernarfon, Beaumaris, Conwy, Harlech) and the Welsh equivalents are all worth consideration.

I do wonder what Edward I, the Hammer of the Scots (yes, he hammered us, but into a nation he did not expect!) would think, probably be spitting feathers over the Welsh flag fluttering over the four castles.

It depends on your interests.