3 options....help us !

I would vote for England and Scotland-so much to see. If I am guessing correctly and you are from Quebec, a trip to England would help you understand the rest of Canada. And it would be good for your children to have an opportunity and motivation to practice their English, being the single most useful language when you're traveling in Europe.
With regards to your itinerary, are your children Harry Potter Fans? And you must add York to your itinerary. What are your interests in England-outdoors, history, cathedrals?
This will be a wonderful trip!

Itinerary #1. Drop the car at Oxford, Salisbury or York and train into London.

yes we are from Quebec. Don'.t worry we all very know the rest of Canada, we have been in all provinces at one time or another !

My kids dont care about Harry Potter at all. I dont think they even knew who it is !

History, outdoors, Cathedral..we love all those ! Juste a mix of them (not only cities) would be great !

Your Scotland/England option will probably provide temperate (though possibly wet) weather throughout.

Option #2 is the likeliest to expose you to rather a lot of hot weather. Even Annecy was miserable when I was there in June 2017.

Option #3 sort of falls in between, weather-wise. The northern Spanish coast from Bilbao to Santiago de Compostela (A Coruna excepted) is generally coolish and overcast, and of course if you get up at altitude in the Pyrenees, you won't be hot. Toulouse, Carcassonne and Leon can be miserable in the summer. I have no personal experience with Bordeaux or the Dordogne. I think 2 nights around Santiago de Compostela is rather skimpy. Galicia is lovely, though the scenery isn't quite as dramatic as that of the Spanish Basque Country.

If you opt for #3, check out the Picos de Europa. That's the prettiest countryside I've seen in Spain.

I agree with acraven, I think that the Picos de Europa/Northern Spain may be an interesting take on option #3... summer time is probably the best time to travel in the area.

One could start in Toulouse (or San Sebastián) and end at Santiago de Compostela.
With potential stops at: Pau, Bayonne, San Sebastián, Bilbao, Santillana del Mar, Altamira caves, Picos de Europa, Potes, Covadonga, Oviedo etc.

It will be a good trip food-wise too as you will have an interesting contrast between the distinct Basque, Cantabrian/Asturian, and Galician cuisines. Lonely Planet recently revealed their top 20 food experiences for 2018 and Pintxos in San Sebastián was ranked number one.

Just google Picos de Europa and you will see why it is so spectacular :)

You might consider Durham while you're in northern England. It may even be a good location to stay in when going to Hadrian's wall. It is a compact university town with a beautiful cathedral and a nice walking path along the river. We found it very restful and quiet(except for students) when we were there in June.
Because most of the rest of Canada was settled by English, I think knowledge of English history would enrich your understanding of Canada's history, as understanding of Spanish history in America is helpful to us in understanding Florida, Texas and other western states.

That's why it will be a tough choice. All regions have their upside and downside.

You must have guess that all the three options are not very well plan, they are just basic ideas that, of course, need some tuning.

Traveling means that we always have to make some tough decisons. We cant see all and we have to make the best of it. Maybe that in our 25-26 days we can select 4-5 base and do daytrip from there by car. That something we would like. The hard part would be the choose carefully those bases.

For bases, I suggest London(of course), York, Edinburgh, Glascow, maybe Bath. You can easily do lots of great day trips from London by train, but that could be pricey for a family (purchasing tickets 2 months in advance and leaving after 9:30 in the morning are your friends). You could also consider a trip to Southern Wales-Cardiff-St. Fagan's is a great outdoor history park that should appeal to your children. It was one of my favorite travel experiences. The National Museum(free admission) in Edinburgh should really appeal to your children. You might want to rent car in Glasgow and do the driving part of your tour first. You will not want a car in Edinburgh. Glasgow is closely to Loch Lomond than is Edinburgh. If you have not already done so, get Rick's Great Britain book to help you plan.

I'm enough of a professional cycling fan that when I hear Pau, my mind goes to the Tour de France (it's a regular depart/arrivee town for the Pyrennes part of the race) They haven't announced the full route yet, but the race is from July 6-28 in 2019 so be aware of that when planning a French holiday in July.

If you do find yourself convenient to a stage route, the kids might enjoy the publicity caravan- the daily parade of tour sponsors with floats and thrown items that covers the course ahead of the riders themselves. (Surveys show that for French residents, the parade is much of a draw as the race itself)

http://www.cyclingnews.com/features/waiting-for-the-tour-de-france-gallery-1/

Speaking of La Tour de France, it always comes through the Vaucluse, going up Mont Ventoux. I’m there now and I guarantee you there are no beaches, though there’s history, good food and even a craft beer or two. Most of what you’ve outlined in choice 2 is very hot in July and August. I’d opt for the Dordogne, Bordeaux, Les Landes south of Bordeaux, and do your Pyrénées, Northern Spain tour. You could still hit Carcassonne on the way back, drop the car in Toulouse and fly out.

My grandson turned 18 last month. As a child he wasn't interested in Harry Potter either, never heard him mention the name.

Of the three options, I vote for Option 2. What are your priorities and travel interests?

I would vote for Option #1. Simple reason: you have the best chance to escape brutal hot weather up there. Unless you are really used to the heat (and I don't think I've met any Canadians yet who are), if you get caught in a summer heat wave (more likely the further south you go) it can really make you miserable - just ask anyone who experienced that this past summer!

I now plan my summer trips to avoid anyplace that gets too hot. Scotland and England can warm up too, but would be the mildest of any of your choices. It's a great area to visit, too, in any weather.

Referring to the history pertaining to Vaucluse, there is some grim stuff there. I was there once...in July 1999 and saw the resistance memorial there. There was a horrific battle there where the Resistance fighters were destroyed.

I would pick option #1 also. Unless I have daily access to the beach or a pool, I am just not a fan of heat while trying to sight see. As far a a base for day trips, you have many nice locations where you can rent a cottage which is so nice to do especially when traveling with children. Either the Cotswold or Lake District area are wonderful places to do this. I traveled with a friend and her two children to the Lake District a few years ago and we rented a cottage on a farm. The kids loved helping to let the ducks out in the morning and collect eggs. They also got to help feed the baby lambs. I think they would have stayed on the farm the entire time had we let them, but there are many day excursions that were fun for all of us.

My family's first trip to Europe came when the boys were 8 and 11. Our trip started out similar to your Option 1 - three nights in Glasgow, rent a car and drive to Inverary, three nights there, three nights in Edinburgh, three nights in the Borders near Newlands, then almost a week in Windsor as our base to see Legoland, Stonehenge, Ashdown Forest for the Winnie-the-Pooh fan, and a day trip to London via train. We focused on playgrounds and castles and had a great time.

Thanks to all for all those answers. they are welcome but it makes my choice being tougher ! from what I read, there's no bad option nor perfect one. I guess we will gave to read some guide books and have a family chat !

The main advantage of France wis the fact that our kids would fully understand the language (beside local expressions !)