Daughter, boyfriend and I bought a Quer Durch Deutschland (all across Germany) ticket from the automat in the main train station for 54 euro and got on the train on track 24. This train travels down the Rhine and leaves every hour. The conducter started checking tickets right away when the train started at 08:53 and when I showed him our group ticket, while getting out our regular Frankfurt tickets, he just waved those away, saying the 7 min. wasn't a big deal. Like the Länder tickets, these Quer Durch Deutschland tickets are valid after 09:00 weekdays. We got off the train in Assmanshausen at 10:11, and had expensive cups of coffee in the Kronen hotel. What a gorgeous place! Looks perfect for a weekend away. Walked to the KD boat dock and got tickets to St. Goar. Mine was 13.80 with my 20% discount that one gets if you show them your train ticket, and the "kids" got student discounts of 50% off. Boarded the ship at 10:45 and we arrived in St. Goar at 11:55. Nice trip down the Rhine, with gorgeous weather. Perfect for photos. After arriving in St. Goar, we sat and had lunch as we had just missed the little train up to Burg Rheinfels. Flammkuchen and bratwurst with sauerkraut were fairly tasty. The train cost 3.50 € p.p. round trip. Having walked up to this castle several times, the train cost is worth it, as the walk is fairly strenunous.
Tickets into the castle were 4 € each and we spent about an hour and a half exploring all the tunnels, etc. This is my favorite castle on the Rhine and it is a lot of fun. The flashlight app on my i-phone came in handy several times in the dark tunnels. Good shoes are a must! Got a nice little history book about the castle for .50 € and in English. We then rode the train back down into town, and after visiting both of the lovely, old churches, (both are well worth a visit) we decided to take the ferry across the river to St. Goarshausen. The ferry ride is interesting and certainly saved us a lot of time rather than riding the train to Koblenz and waiting for the next train to head back down the other side of the Rhine. We had about a 25 min. wait on the train and the ride to Rüdesheim was only about 30 min. Rüdesheim is Rüdesheim, one of my least favorite towns on the Rhine, whose only saving grace is the chair lift that takes you up to the Niederwald monument. It is beautiful riding over the vineyards, and quiet except for the many birds. Lovely! The stores in this town offer so much tacky kitsch, that it is almost sad to walk through here. The food here is usually pretty decent though and not over-priced. The train station here is odd, as there is probably a million people a year passing through here, yet the spot for a store has been empty for years. So, no water, no snacks, no ice cream and no toilets. The closest toilets are at the wine museum in the Bromserburg. They are always disgustingly smelly, with no soap.
The wine museum is kind of interesting, with good audio guides. If you are into wine, then you might like this museum. Plus this is quite an old Staufen castle and interesting on its' own. Most people enjoy having a Rüdesheimer coffee, which will cost you about 6.50 €. The show they put on while making it is a big part of the price. The train to Frankfurt runs every hour and we arrived back in town fairly exhausted but with suntans from sitting on the deck of the ship and walking around the towns. Fortunately, these trains are very new, with A/C, toilets and nice seats, and the doors have steps, and are lower to the ground, which makes it easier for seniors or those with suitcases. Having done this trip a number of times, here are my tips and suggestions. The ships stop at Rüdesheim and then Bingen and then Assmanshausen, so check the schedule for the train and the ships to see which stop will work best for you. Always ask about discounts for seniors, students and with your train ticket. Having toured the Marksburg castle a number of times, it didn't fit in our schedule this time. Have also been quite disappointed with the tour guides at the Marksburg too, as family and friends were unable to understand the extremely poor English, and the very bored delivery of the tour by these guides. So, in my opinion, visiting Rheinfels was a much better use of our time and far more impressive. If you only have time to visit 1 castle on the Rhine, than this one gets my vote.
I'm going to defend much-maligned Rüdesheim. Yes, there are too many kitschy souvenir sellers, but you could also say the same for Bacharach, St. Goar, Rothenburg odT (which is overflowing with them), and even to just about every Weihnachtsmarkt. Deflect your eyes from the glaze of souvernir merchants, though, and it really is an attractive little town. But for me, the one unique thing you'll find there that you won't see anywhere else- a large choice of restaurants offering live Schlager performances. Love it or hate it (I have mixed feelings on the genre, but in my secret shame, I kind of like it...), where else can you find such a quintessitially modern German experience?