Devo, great work on organising the trip! You have some daunting planning ahead - so many options...
If you get a chance to get to Plzn in Czech Republic, the Pilsner Urquell brewery tour is well worth it. You start at "Beer World" and end up in the miles of cellars underneath the brewery sipping fresh pilsner from wooden casks. I ended up staying a bit longer with the guy pouring the beer (luckily his only English was "more?").
These photos were taken on that wonderful day...
The brewery buildings;
That famous gate (featured on the Pilsner Urquell label);
And the result of too many samples;
I can also recommend a wander along Oranienburger Strasse (love saying that) in Berlin. Plenty of bullet-hole ridden walls and a grungy, eclectic mix of synagogues and bars. We bar crawled along there for my 25th birthday and one bar looks like a metal workshop, complete with fire-breathing dragon over the bar. Seriously!
There's plenty of places along there to try some sour Berliner Weisse. Try it on its own, but the locals like it with red or green cordial.
As Warren said, Paris is good enough to just wander around. Don't buy any beers on Champs Elysses - kind of pricey! Here's a photo of the Paris Metro system, taken through the eyes of someone who's enjoyed too many Kroenenbourgs;
Good luck with the planning - looking forward to a quiet pint soon. Cheers.
edit: Here's some Berlin bullet holes to go on with. Seriously, this has to be my favourite European capital, so much history, so much going on....