We will be in Germany in July with our 2 children and need to get to Paris. Wondering if we should take the train or fly - could leave from either Frankfurt or Munich. If train - should we buy tickets here or in Germany?
If you can get SparNight fares, the night train from either city would be your best train choice. You could book bunks in a four-person couchette and have it all to yourselves. Normally you can book online up to 90 days in advance at http://buchung.nachtzugreise.de, but new timetables will be issued in June so currently July bookings are not allowed. Popular night trains often sell out so it's best to book them as soon as possible. If you take day trains, you can wait until you get to Germany to book them.
Your best airline choice would be AirBerlin, a discount carrier. It has direct flights from Munich to Paris. The sooner you book, the cheaper the price.