L.L.
Hi B.,
it is great that you are planning on visiting the Czech Republic. I am actually from there, my parents live just outside of Prague. If you will get a chance to go, Prague is beautiful, but there are other places to visit like the town of Cesky Krumlov in the southern Bohemia and also Karlovy Vary which is a spa town in the western part of the CR. There are pretty mountains in the north called Krkonose, the town of Spindleruv Mlyn is very nice.
About Germany, Bavaria is beautiful. Last spring we took a car road trip through Germany to Croatia, it was great and beautiful.
I have two girls 6 and almost 4 and I traveled with them every year since they were born, it is an ordeal. But it is all worth it once you get there. I am just thinking about having a carseat for your baby and also for the 4-year-old so that she can sleep in the car. Lightweight stroller is very handy for the airport and later on. Wipes can be now bought in the supermarkets even in the CR, but have an extra pack of different sizes ziploc bags, not yet so common overseas.
Some people don't travel without portable DVD player, can be great on the plane, have the battery charged before. To use it later on you have to have a charger and the thing (sorry, I cannot remember the name) that converts to the European electrical outlet.
Have a great trip!!!
L.