Family Euro trip - itinerary help

I would simply add day trips to London and Paris. You will be amazed at the number of things to do in those two amazing great capital cities and centers of culture. I would spend 7 days in each, and do a day trip or two away from the city. From London, you could go to Bath, or to Oxford. You can do Royals stuff. You can go to the seaside. You can do a bus tour of some local area. If you are up to driving (not that hard really), you could rent a car and go on a rural outing.

For Paris, there are a ton of things to do in that area. You will need to find something for your 5 YO. Zoos? Parks?

December is not the coldest time in Europe, that will typically be January and February. It's unlikely that you'll have snow in London in December (and Edinburgh) however the chances increase in January and February.

For me I would spend five days in London and three in Paris. There's more to see and do in London, particularly with young children. Then travel via train to York for two days and then on to Edinburgh for the remainder before taking a flight to Paris from Edinburgh.

Be aware though that in mid December it'll be getting dark by about 3.30 pm.

You can go to the seaside.

In December?

I agree with Paul and would stick to London and Paris. I would certainly not add two flight days into the mix by detouring to Spain, besides which either Barcelona or Madrid (with side-trips) is worth at least 5 nights. Leave Spain for a separate trip.

I have bever been to Belgium, but by nearly all accounts Brussels isn't very exciting (and London and Paris are), and I don't know that Bruges will be very charming in December.

If this this is your first visit, I think 3 days in London is short to the point of craziness. There is tons to do there, with many options that should be appealing to children. I wouldn't even want to take the time to go to York for a couple of dsys. It will be colder and darker there.

Two locations is a good idea. I would also suggest London-Brugge-Paris, all easy train trips trains, 6+2+6 nights. That gives you an old town in the middle of your two big cities.
You say flights are fixed, if they weren't, another option is flying into Edinburgh and doing Edinburgh+London+Paris, all by train.
Both London and Paris are suited to day trips out of the capital. For example, London:Windsor, Paris:Versailles; compare and contrast royal castles. Plus lots more.

"December is not the coldest time in Europe" - Yes, but it does have the shortest days. On 15th December, sunrise in London is 07:59 (8 am), sunset 15:51 (yes, just before 4 pm). It will be dark and grey, be prepared for that.

are you arriving in early, mid or late December?

Makes a difference as to what to do, where.

TOO much travel involved. Suggest leaving out Barcelona for another trip. Three days in London is way too little.

I hope you don't mind crappy weather. It is cold in Northern Europe in December. It gets dark about 4:30.

Suggest even saving Scotland for another trip.

England including London, go with minimum of a week.

London for your base and visit places like Canterbury, Stonehenge, Windsor and York.

Paris you need about a week. You can see Bruge in a day. Brussels is not my favorite city in Europe.

I would just do an even split between Paris and London. We did this last summer and had a blast. There are a ton of things to do in both cities and you can also do day trips. We took the Eurostar between London and Paris and it was great

Put me in the 2-city camp, but if you are determined to add a third, then Amsterdam would be my sugggestion. I don't think there's much for kids to enjoy in Brussels/Bruges, but Amsterdam is another story altogether. Fly from London City Airport to A'dam, then train to Paris.

Either way, now's the time to buy those Eurostar train tickets while there are still cheap ones available.

Thank you all for your suggestions. I think I am going to take the heed and stick to London and Paris. We arrive in London in December 22 and were originally planning on departing on 25 to our middle stop. But I realized that everything will be closed on 24/25 so we might need like need there. So here’s what we might do - stay in London from 22-28 - bake in some day trips (also any pointers on the Harry Potter experience?) and stay in Paris from 29-4th Jan and include some day trips. That takes the stress out of moving multiple times.
Now that locations are penciled in - do you all have must do recommendations outside of the regular touristy stuff in either London and Paris. We are art/history buffs and kids enjoy sciencey stuff. We will hit the usual suspects but wanted to get your recommendation for other things.
And lastly we will be getting a airbnb since we have another family of 4 going with us - what area do you recommend we stay in London as well as Paris.
Thank you so much for all your help!

I didn't realise you were attempting this trip OVER Christmas. Do not attempt to travel on 25th December. Everything will be closed and there will be no transport. You need to plan that day carefully, walk everywhere and wherever you plan to eat, check it is open. Also avoid travelling on 23rd/24th or 26th. These are heavy travelling days and very busy.

Eurostar for Sat 29th Dec will also likely to be busy. If this is a final plan, I would book soon. Prices for that day are currently in the range £67 to £84, but they will only go up. Website: https://www.eurostar.com/