Where to go for a child-friendly vacation in Europe?

It's a bit out of your way, but when I visited Slovenia it struck me as a great place to take kids. It's a very "fairytale" sort of place, full of old castles and deep mysterious caves and folklore about dragons. There's also Lake Bled, which seems like an extremely kid-friendly place to spend a few days (lots of rowing around in boats and ducks to feed, and the obligatory castle), and the Lippizaner stud farm (AKA "oooooo look at the horsies!") towards the Italian border. There's also lots of hiking and some adventure tourism, though I think they're probably too little. That said I don't know that I'd trek halfway across Europe for it. But it really is a superb place to take kids.

We spent about a week in Stockholm with our then 5 1/2 year old daughter in summer 2011. She had a great time at http://www.visitstockholm.com/en/To-Do/Attractions/junibacken/859 (She spent hours in Pippi Longstocking's house playing Don't Touch the Floor); we did a day trip to http://www.visitstockholm.com/en/To-Do/Attractions/birka/1108, and http://www.visitstockholm.com/en/To-Do/Attractions/skansen-open-air-museum/890 and http://www.visitstockholm.com/en/To-Do/Attractions/the-vasa-museum/142 were a lot of fun. The thing she loved most of all, though, was http://www.visitstockholm.com/en/To-Do/Attractions/tom-tit-s-experiment/902. We were there from the time it opened to the time it closed (11 am - 6pm, IIRC), and she didn't want to leave. She still talks about how much fun she had there. If you go, bring extra clothes for the kids, as my daughter got soaked in the water area (I had her go play in the wind tunnel for a while to dry her off a bit, and then we were able to buy her some dry clothes on the way home.)

I just got back from a vacation in Scotland with my kids, who are 2 and 4. We stayed near Aberfoyle, in Strlingshire. About 45 minutes drive from Glasgow airport. It's not exactly the Highlands, though the Highland boundary fault runs through the area. There are http://www.lochlomond-trossachs.org/visiting/short-to-moderate-distance-walks/menu-id-328.html in and around the fault area that start in Aberfoyle, though some of them may be a bit much for your 4 year old. We did http://www.lochlomond-trossachs.org/images/stories/Visiting/PDF/ActivitiesLeaflets/Balmaha%20inside.pdf (pdf), along the banks of Loch Lomond, that the kids enjoyed. Great views of Ben Lomond, it also passes the pier where you can take a boat over to the conservation village of Luss. My kids were entertained the whole time, they enjoyed the walks and the wildlife, we also did http://www.trosssachstrekking.com/, and visited the aquarium in Balloch. Glasgow itself has lots of activities that will keep your kids interested if the nature activities start to bore them, in particular the http://www.glasgowsciencecentre.org/ is good fun.

I think I'd stay in south-western France / Northern Spain so as not to waste time on traveling days. There are tons to see and do, both culture and nature. How about renting a house on the edge of the Pyrenees as your base, and then making day-trips from there? http://en.wikipedia.org/wiki/Carcassonne is fascinating, and so is http://en.wikipedia.org/wiki/Monts%C3%83%C2%A9gur, you can combine it with stories of knights in shining armor and crusades as you see fit. You can also visit the pilgrim route to Santiago. We are not religious, but my kids loved when excursions were combined with "stories" like this. Also, going up in the mountains and hiking a bit will be nice at that time of year. There are the http://www.salvador-dali.org/museus/en_index.html north of Barcelona for another fun day. My dad once went on an excursion somewhere outside Bordeaux, where they gathered shellfish while the tide was out, and then cooked them for lunch, he talked about that trip for ages after. I've tried to find the tour on the webs, but couldn't. Instead I found http://www.dailymail.co.uk/travel/article-2169810/Cap-Ferret-holidays-Sand-dunes-cycle-trails-scrummy-seafood.html, and found it inspiring, even though you said you weren't interested in beaches. My kids (and nephews and nieces) really enjoy foraging and cooking on open fires. Bordeaux in itself is a charming city, and I've read that the architecture museum is famous for it's children's activities. Albi is on my personal to-do list, but I'm not sure wether it's attractions are child-friendly. Scandinavia, including Iceland, is beautiful, but the distances are huge. Whereas in the rest of Europe there is a lot to see within a short radius almost everywhere. Still, we went to Stockholm with 7 children a couple of years ago, and had a great time.

I have put repeated pitches in for staying at Les Olivettes in Lourmarin (where Peter Mayle lives, I believe). It has a pool and is a lovely place to stay--each room is a suite with a kitchen, which is great with kids. It's near/in the Louberon, and there's a lot of gentle hikes--I particularly liked the ochre pits at Roustrel--a former quarry for the mineral, it's beautiful orange sandy hills. Really nice. Plus, on the way (or while you're there) cool places like Nimes, Arles, Aix, Avignon--so much great stuff to see.

http://www.atlasobscura.com/search?utf8=%E2%9C%93&q=&lat=47.497912&lng=19.04023499999994&formatted_address=Budapest%2C+Hungary and http://www.atlasobscura.com/search?utf8=%E2%9C%93&q=&lat=41.00527&lng=28.976959999999963&formatted_address=Istanbul%2C+Turkey have a great mixture of culture/museums for everyone, amazing food (and wine!), great walking neighborhoods, awesome parks, endlessly fascinating rivers/waterways, and both are cheaper than parts of western Europe.

I agree the food in Italy is great but if you're in Toulouse, well you're in Southwest France where the food is also amazing. Aside from food, that area also has some of the best and most famous caves in the world, as well as scenic hilltop towns and plenty of things to do and see. The Dordogne is full ofhttp://www.northofthedordogne.com/caves.php and http://www.telegraph.co.uk/travel/destination/france/91708/Dordogne-travel-guide.html It might be selfish but many of these caves such as Font de Gaume may be closing soon so this may be one of the last chances to see them. You can base your stay at someplace like http://www.sarlat-tourisme.com/en/ (a gorgeous though touristy village) or http://leseyzies-tourist.info/. From my experiences in that area, the whole place just seemed built for kids.

Another place I was just researching (as I'm going to a wedding there soon) is the Amalfi Coast - Sorrento, Naples, Positano, Capri, Pompeii...it seems like very a high concentration of interesting and beautiful places in a small space.

We did a driving trip from Germany to Italy when our kids were about 5, 7 and 9. Would the kids like to go visit castles and castle ruins? If so, look a little further into Germany. I know you said you didn't want a Disneyland experience, but I can say that Legoland in Germany is pretty awesome. Lots of rides, but also lots of physical fun for kids - outdoor climbing gyms etc. Our kids loved it and it was good bait to tell the kids "Only 3 days til we get to Legoland" for the days that were a little boring for them.