This one's specifically for @ZenNudist although also of course for the OP:
I suspect after what you wrote that I'm falling on deaf ears, and I acknowledge that I am quite easily satisfied, but nonetheless:
If you have kids in tow (depending on their age, of course!), try the science museum. It's in two parts, with the 'Spectrum' part being particularly full of hands-on activities and containing oddities such as a car designed to also function as a boat - just drive it straight into a lake and break out the paddles...
Spoiler, it didn't work as they could never get them watertight enough.
Behind the museum is a long linear park built on what had been railway lines leading out of town from Anhalter Bahnhof. It became obsolete after the Wall was built, but many of the tracks remain.
The Allied Museum in Dahlem is free, is built at the former US military cinema, and has the original Checkpoint Charlie checkpoint building, planes, a GDR watchtower, etc.
To get to it from the U-Bahn (Oskar-Helene Heim), , you are going past a building on your right that was built by the Nazis as Luftwaffe headquarters, then commandeered post-war by the American military as THEIR headquarters. Many of the apartment buildings around are former US military baracks.
One station further out of town on the same line and you are in a housing that looks like a lovely idyll of two storey homes, but was actually built by the Nazis as housing for SS elites.
Plenty of Nazi architecture: the football stadium, or the Finance ministry opposite the Topographie des Terrors which, as other people have said, is definitely worth a visit.
There is also a GDR watchtower tucked in behind Potsdamer Platz.
There's a very large section of memorial/former wall at Bernauer Strasse ( also free).
The Stasi museum, at the former Stasi headquarters, is also worth a visit.
The Communication Museum might be of (low-key) interest. Entry is very cheap and it has a working model of the mail delivery system working with compressed air that was in widespread use before WW2 put an end to it.
Food: I personally find quite a lot of German food dull. However. the whole 'divided city' thing has left an interesting food legacy. The former East brought guest workers from Vietnam, and many are still here as particularly in the East of the city. If you avoid places that are trying to hedge their bets by offering Vietnamese AND Thai AND sushi, and go for places offering only Vietnamese, you are likely to get very good food.
The West had a problem attracting workers to a city surrounded by a wall and sitting within the territory of another country, and dealt with it by importing workers from Turk, Italy, and Yugoslavia. Many of the Italians and Yugoslavians later returned home, though there is still excellent Italian ice cream (though most places have just closed for the season), and quite a high proportion of restaurants featuring food from former Yugoslavia.
The Turks have a LOT of food places with excellent quality food. I'm not just talking about kebabs/döner (although the quality is pretty good there too!), but things like Adana Kebab, gözleme (made on the spot with the filling of your choice and usually sold at businesses specialised in making only that), simit or açma (if you like Turkish breads, these are available at any Turkish grocery store), freshly made Turkish sweets, etc.
Kantstrasse, if you are anywhere near, has a lot of good Chinese and Vietnamese food options, including things like hand-pulled noodles.