Where to spend one month abroad this summer?

Perhaps somewhere like one of the lake towns in Austria? Fab scenery, good walks with gondolas to take you to higher meadows. The lakes offer swimming, boating etc. Seefeld, Kitzbuhl, come to mind offhand but lots of others. Day trips to Innsbruck, Salzberg, into Germany.

Depending on how important "good" weather is to you, I think Scotland would be a wonderful place to spend a month. I'd suggest Edinburgh as your 3-week base (lots of good day trips from there - Glasgow, St. Andrews, Stirling, etc. all within easy reach by public transport). Scotland has amazing natural wonders all over, and attractive beaches and coastal areas are easily reachable from Edinburgh as well. For your 1-week somewhere else, you could explore the Highlands, perhaps with a base in Inverness (an underrated Highland town with great transport links and lots of things nearby such as Loch Ness / Urquhart Castle, battlefield at Culloden, Dunrobin Castle, Cairngorms National Park, etc.).

I find Scottish summers to be very comfortable with extremely long days (still sunlight after 10:30 pm), but the weather is prone to change (understatement!) and cooler than some would like for their summer vacation. It might be a nice counterbalance to your prior trips to Italy for example.

How about Basque Spain? We stayed in the Intxaurrondo neighborhood of San Sebastián for a week and never ran out of things to do. There is an aquarium and a crazy old amusement park up on the hill. The food is insane. On the way to Bilbao is Basque Coast Geopark, which Google AI says is "famous for its dramatic flysch formations: tilted, alternating layers of hard sandstone and soft shale, recording 60 million years of Earth's history, including the dinosaur extinction." In Bilbao there is a "bridge" that carries cars across the river like a crane. Get a car, though. That was my mistake.
For your week somewhere else, you can take a ferry to Ireland or England.

May not have the best food, but the summer time is lovely in southern Sweden, especially June-July. I've spent the last 3 years spending some portion of the summer in Sweden. I think finding a mid sized city (not too big), and renting an apartment for a month would be nice, along with a car so you can explore the surrounding area.

There are always many sites to see here and there, good hiking, museums, lakes for swimming, castles, charming villages/towns. The best part I've pretty much been the only non Swedish person around, it's all been locals, even at the height of summer. A very memorable experience. I'd take a look at places like Lund, Karlstad, Kalmar, or Uppsala as potential homebases in southern Sweden.

So I've been to San Sebastian twice and this was a thought for the one month abroad this summer. I would certainly rent a car. It would hit the good food, beach boxes. Wondering if there's enough if the immediate area to occupy us though.