I took KD from Rudesheim to St. Goar.

Got off in St. Goar and toured the town and castle.

Took the train to Bacarach and toured around the town.

Took the train to Bingen and the ferry back across to Rudesheim.

It took the better part of the day.

Thanks for your input. Not exactly what I wanted to know but it is a start. Can you jump on/off any KD boats at will? Did you stay in Rudesheim? Would you recommend a place?

www.k-d.com for schedules that show in season there are frequent enough boat service to hop off in one cutesy riverside town or trek up to some ruined or intact castle (Marksburg is about the only one Napoleon or some other marauders didn't turn into ruins!) - with a ticket you can get on and off at will I believe though ask at the boat ticket window to make sure as things may have changed since I took it.

Most folks actually on boats I've been on get bored after a while so I'd buy a one-way downstream ticket - significantly faster, starting in Rudesheim, where many servies commence - some come from upriver at Mainz but the Mainz to Rudesheim part ain't all that scenic but would be of interest to folks liking riverside industrial works and freight barges (which you see all up and down the Rhine Gorge - a real working river) anyway get on at Rudesheim because the boats start from there so you can nab a desirable seat up front along the rails so you can get an eagle's eye view of both sides of the river - by the time the boat docks at Bingen across the way those seats may well be gone.
Again I would hesitate to recommend a round trip journey - trains can take you quickly back from Koblenz or other city the boats dock at, like Boppard - some say the finer scenery ends at Boppard but to me it's Koblenz, where high on a cliff on the east side to the Rhine, right at the confluence with the Mosel is a huge old palace -an awesome site to me.
And Koblenz is an inviting city - a large city with loads of shopping streets, restaurants, etc. Check out Deutsches-Eck, a monument right where the Mosel and Rhine rivers meet - a huge equestrian statue of Kaiser Wilhelm once graced the plinth/pedestal until WW2 when just after the war an American GI for fun blew it up with his huge gun (told to me by the manager of the campsite that still sits opposite Deutsches Eck, which now is still a huge statue but one devoted to German Unity and Uber famous in Germany and Germans flock to see it.
Try to spend a leisurely day on this part of The Rhine - trek up to Marksburg Castle from its boat dock (or take the lift) - walk perhaps on riverside paths or paths thru vineyards from one riverside town to another.

If traveling on trains very much in Germany then check out the German Raialpass, which becomes cheaper per day the more days you buy on it and it lets you hop any train anytime, including city S-Bahn lines that serve as metros inside cities. This pass is also good in full on K-D boats on the Rhine and between Koblenz and Cochem on the Mosel - many think the Mosel Valley is even cuter than the Rhine and Cochem is a fairy-tale dream wine town at one of the most scenic parts of the whole Mosel River - trains go to Mosel regularly as well making it a viable base from which to train to Rudesheim, via a change of trains in Koblenz and take the boat leisurely back to Koblenz.
A new version of the German Railpass in 2013 has its validity extending into parts of Austria, northern Italy and Belgium and the Czech Republic. A Twin Pass is for two folks traveling together - two names on one pass and again flexbility is the key - hop any train anytime with few exceptions like overnight trains, on which the pass is also valid but you pay extra for option sleeping accommodations.

For loads of great stuff on German trains I always spotlight these IMO fab sources - www.bahn.de/en - the German Railways official site with schedules and sample fares to compare to the pass; www.seat61.com; http://www.budgeteuropetravel.com/id9.html and www.ricksteves.com.

PalenQ: I can't thank you enough for these great tips. We will definitely then look for lodging in Rudesheim probably for 2 nights to offload my jet lag and sightsee. After 2 days in the middle Rhine area, it will be South to the Black forest and maybe a pop across the border to Switzerland. Vielen Dank. Tom

maybe a pop across the border to Switzerland. Vielen Dank. Tom>

Dank u wel too!

Basel, Switzerland for a city is a wonderful city and just across the border but also consider going to Schlauffhausen, a Swiss town surrounded by Germany and a sweet town but the reason for going there is to walk along the Rhine to the Rhine Falls, a thundering cascade that is very popular with Germans and Swiss both - there is actually a train station right at the falls - trains from Basel, Germany I believe.

Cheers

More great advice, and I/we can use all I/we can get. We will check out Basel and/or Schlauffhausen in Switzerland. Any recommendations of towns/guest houses/b and b's in the Black Forest area? We are thinking of a 2 night stay in the BF and maybe 1 night in Switzerland.

I very much liked the BF towns of Gengenbach and/or Staufen near Frieburg im Breisgau.
Check out whether they could fit into your circuit geographically-speaking! Both have town internet sites.

Any recommendations of towns/guest houses/b and b's in the Black Forest area?>

well besides mokka's recommendations (which IME I would value highly) you could take the scenic train line thru the Black Forest up to Titisee (sp?) a high Alpine lake that is a favorite hiking place for locals - I saw several nice towns up there - I just did a day trip but one town seemed nice - I'll have to look it up - but the train ride is very very nice if you do not have a car.

We are thinking about 1 night in a very rural town in the Blackforest, perhaps Schiltach, and then 2 nights in/around Freiburg. From Freiburg, we could do a day trip into Switzerland. We will have a car for the duration of the trip so getting around should be no problem. I also just noticed that there are a lot of Castle Hotels to choose from in Germany. I still owe my wife for not agreeing to stay in one when we were in Ireland. Maybe I can make it up to her. Any recommendations on castle hotels in/around the Black Forest? Ah, too many choices!!

The drive from the Black Forest area via Ulm over to the Fussen area is very very scenic nearly the whole way - fussen is just a few miles from Austria thru the river gap to Reutte, a nice old town with a castle - short drive from there via Garmisch to Innsbruck and then hook back up to Munich if that is in your plans.