We are hoping to do the RS tour of Paris next summer and then take his GAS trip, but we have 8-9 days in between tours. We can either stay in Paris for a few more days (8-9 days) or go to several other places along the way. Or we can just go to St Goar directly. What is an easy way for us to get there directly? If we decide to meander, what are cute places either in France and/Germany where we could spend some time along the way. I would love to see Rothenburg or Alsace, but I don't know if this is feasible. Thanks for your help/advice.
If you are going early enough in the year, Keukenhof Gardens in Holland are very special. 7 million blooming tulips are an extraordinary sight. Consider Bruge, Haarlem, Amsterdam. Keukenhof can be taken in as a day trip from Haarlem. We, with an itinerary already established, skipped Amsterdam to take in Keukenhof and have no regrets at all.
Go to the Flickr website and search for pics of the Keukenhof Garden to get some idea of how extraordinary this place is.
All your travel connections can be done easily by rail. Just familiarize yourself with the German Bahn website for possible connections between the places you want to go. As you are planning RS tours you are already familiar with the one bag concept and will find travel by train very easy to do.
I would plan at least an extra day or two in Paris at the at the end of the tour. You can see some sites not included in the tour plus rest up for the next tour. You can take the train to Strasbourg which is in the Alsace area and about a 4-5 hour train trip from St. Goar. We arrived in St Goar about 3 days before our GAS tour. It is so charming. We took a day trip on the train to Kohl to see the DOM and another Rhine cruise that was not included in the GAS tour. I love the GAS tour. Get the train schedules from this website. It will help you plan whatever you do.