coming from Austria and main purpose is to take half day trip + on the Rhine !!! say between Bacharach ,St Goar, Koblenz we are travelling with eurorail passes Think we would like to make our way to Burgundy in France Then onto Paris . Sept is the month OK am l looking at some worth while ? we are both 75 so long hikes are not probable what would be time difference on each journey
"...main purpose is to take half day trip + on the Rhine !!! say between Bacharach ,St Goar, Koblenz"
Your plan is unclear; we have no idea what time you will reach the Rhine or how many days/nights you have for each location.
A Rhine cruise doesn't require half a day if done correctly - you should have time to visit a town or two and see a castle as well. The most scenic section of the Rhine takes only about 1.5 hours by cruise boat; from Bingen, cruise NORTH (with the current) to St. Goar and get off there. You'll see a ton of castles along the way. And in St. Goar you can tour Rheinfels Castle.
If you choose to cruise SOUTH from St. Goar to Bingen instead, the trip will require 2 hours 40 minutes instead because of the strong river current - and you will see nothing more.
Bacharach lies between Bingen and St. Goar - but rather than get off in Bingen, you can stay on the boat to St. Goar and then take a train south to Bacharach to see that town if you wish (this is often easier than trying to hop off the boat and then back on the next one since the trains are so much more frequent.)
If your main goal is to visit Bacharach, St. Goar and Koblenz you won't need a cruise to get around. The K-D line ferries operate between these towns and Rick gives more information on using these ferries in his Germany guidebook. September could be a good month to travel since weather usually is pretty good still but no promises. You can find all of Rick's rail tips on our Rail Page and that can help you decide if a railpass is the best fit for your trip. We also offer a Trip Consulting service that can help you fill in some of the blanks of your trip.
"If your main goal is to visit Bacharach, St. Goar and Koblenz you won't need a cruise to get around. The K-D line ferries operate between these towns."
The K-D line offers river cruises: KD WEBSITE
Ferries are operated by other companies - like "Fähre Loreley GmbH & Co. KG" which operates the ferry that connect St. Goar and St. Goarshausen: car/passenger ferry