Yep, this Yank is going to storm the beaches of the Thames for Christmas!
I am bringing my wife and adult kids, along with my daughters, boyfriend, who may become fianc during the trip!
It's his first time overseas, so I am racking my brain for the highlights to see. I've spent enough time of the beaten path in th UK, I forget what I should show a newcomer.
He is a history major, so we will def hit the War Rooms, Imperial War museum etc. I don't mind doing the touristy things on this trip.
Any ideas from the locals (or other travelers) would be welcome!

There are so many quirky and historically significant things to see and do in London that you could spend all day, everyday in the city and still have things to see.

Some of the stranger but fun things, go to No10 Adam Street and get a selfie (it looks so much like No10 Downing St that it'll fool most people).
It's not far from Trafalgar Sq where there is the smallest Police Station in the World, big enough to almost sit one person (now disused but still there - not many know what it is even if they see it).
Climb the Monument (to the great fire of 1666).
And then there's a quick stop for afternoon tea in the cript at St Martins-in-the-field, just off Trafalgar Square (and the leaded glass window that looks like it's in a warp field).
Something that is often underated is the open-topped bus tours, might be a bit cold at Christmas but a good way to see many parts of the city and you can hop on and off as you like.
The lights across the city from Oxford Circus all the way to Carnaby St are a sight to see.
Tower of London for the history and Crown Jewels (for the ladies )

If you have a car and can travel and if it is more modern(ish) history you want;

Bovingdon Tank Museum, a couple of hours' drive to the south west (if you are a veteran you should get discount), great for the tank buff. They have a collection of Tigers from No1 to King to Jagd that are must sees (at least for me). Great place to lose yourself.

The Imperial War Museum Duxford is not far, a trip north up the M11 motorway towards Cambridge and you can't miss it (jcn 10 IIRC). There are many aircraft from the 8th Air Force on display and planes from all periods along with the land warfare exhibits. Makes a great follow-up trip to the IWM London.
That leads to Cambridge itself, another great city.

I hope you enjoy your stay in our fine city. If there's anything I can help with send me a message.

The Tower of London is always showing the tourists a good time.

https://www.hrp.org.uk/tower-of-london/explore/yeoman-warder-tours/

Thanks for the info. We will definitely do the Tower; I have a huge admiration for the Yoemen Warders. No matter how many times I've been, it is always a good visit.

The royal air force museum in edgeware is worth a visit. Theres a Purdy shop in london if you like shotguns.
Theres a few big football clubs if you are into that, arsenal is the best dont let no one tell you any different
Atb

Definitely do this! It consists of 4x 15minute talks at locations around the Tower. It's historically interesting and very funny..

Is the Jack the Ripper Tour any good?

It really depends on which one you do. We did one that was an early evening walking tour. It was pretty informative and not campy.

This trip, I got a chauffeured van and guide and did a James Bond, Sherlock, Beatles tour for about four hours on Christmas Day. We had a great guide who was in the know on lots of neat trivia.