Years ago my D was a Rotary Exchange student in the Czech Republic. Her sister and I visited, and found the food delicious, if heavy in that rib sticking, meaty eastern European way. Svickova, a beef dish was my favorite, with a sauce over meat and the typical bread dumplings. D loved the fruit dumplings. Great colder season food. Not sure of your time limits, but we found a trip to Terezin, (Theresienstadt in German) memorable. I remember it being about an hour outside Prague. Prague was terribly crowded, but I adored the smaller cities and D loved Czesky Krumlov.
My Paris favorites are the Orangerie and the Rodin Museum. But in both cities, I agree with the advice to leave time for spontaneous wandering. If there are free walking tours, take them and tip generously. I have so enjoyed walking tours this past year, as they can make cities come alive with stories.