The next day you could go to Technik Museum Sinnsheim, which is about half an hour from Speyer, and has both a Concorde and a Tupolev Tu-144 (both of which you can go inside).
All truly marvels of engineering.
The thing you neglect to mention is that the Speyer 747 is suspended 30 meters above the ground. It's breathtaking.
https://simpleflying.com/technik-museum-speyer-lufthansa-boe...
Fair. We had been to Sinnsheim a couple of times before Speyer. In Sinnsheim, they have the Concorde/Tu-144 on poles on top of one of the buildings. So, the 30 meters high suspension of the 747 was not so impressive anymore I guess :).
The museums are also great for kids. We went several times with our daughter and she loved it every time.
I recently visited Stuttgart to go to the Mercedes Benz Museum. They too have a lot of technical stuff of course, and history. Really recommend it!