I'll be travelling from Paris to Koblenz and staying in the area for 2 nights, with no car. I'll be taking river cruise, visit Marksburg Castle and Burg-Elz Castle, then heading to Munchen. Understand that Koblenz is a train hub which could be good as a base, while Boppard has its own charm. Could anyone give me some advice if it would be a big hassle, travelling wise, to stay in Boppard? This will be in Early May.
I'd go down to St. Goar or Bacharach. It's very easy to catch the train up to Koblenz and then transfer there to go down the Mosel toward Burg Eltz. We did that a few months ago and it worked out great. Bacharach is such a pretty little town and made a good home base. Two nights is tight but doable. From Paris I guess you'll be arriving in Köln. If you arrive in the morning you could take a train from there to Braubach to see Marksburg Castle. Then take the boat cruise (usually leaving Braubach at 3:00) to Bacharach (arriving about 6:30). The next day, it's an easy train ride to Koblenz and a transfer up the Mosel toward Burg Eltz. Staying down the Rhine means more travel but it's such a nicer experience than Koblenz. I guess you need to consider how you're getting to Burg Eltz (we hiked) and where you're headed after leaving the Rhine. To save time, cut down on the cruising. St. Goar to Bacharach is the best part. Have fun!
From what I saw of Koblenz (train station area) it doesn't have much charm to it. If you're going to be staying on the Rhine its better to go for the charm...part of the experience. I stayed in Bacharach (lovely town and fabulous people) and found it to be no problem to travel to Marksburg Castle (train and bus). I only walked through Boppard so I can't speak to what its like to stay there but it seemed cute. The place was dead when I was there due to a holiday, something like father's day. If you don't mind a little extra travel time I'd go with Bacharach, a little bit more to do than St. Goar.
I visited the Rhine area this fall and stayed overnight in Rüdesheim, a city that Rick recommends avoiding (I liked it.) We stopped in St. Goar and visited the castle. We also stayed in Cochem on the Mosel and toured their castle. On the drive back to Cologne, we stopped in Koblenz, walked around the Deutsches Eck, and had lunch. In 2006 I spent several nights in Boppard which was fine; we were there during a wine festival, so it's hard to say what it's like otherwise.
I personally don't like the idea of a "base city" because after that warm, cozy feeling from a great meal and Rhine wine, I would rather not get on a train and find my way back to the hotel. None of these cities are far from Koblenz when you have to catch the train to Munich. My suggestion: If money is no object, stay at Zur Krone in Assmannshausen. Otherwise, stay in Bacharach or St. Goar.
Koblenz is quite large and not as atmospheric as the other towns.
Boppard is an excellent choice. It's closer than the other towns to Koblenz, and it's an authentic German town with good dining and hotel choices; some Roman remnants, a nice river promenade, and a fun chairlift ride to a nearby peak overlooking the river. Also, there's a wine festival in Boppard (Bopparder Mai) from May 16-18. However, St. Goar is in the steepest part of the Rhine gorge and more scenic - 3 castles visible from town. It's small but generally very nice, and maybe even better for transport to Marksburg (just ferry across from St. Goar and take the train north to Braubach; from Boppard, you change trains in Koblenz for Braubach.)
Bacharach is an attractive town that's worth a visit but a bit too far south, IMO, for your itinerary, and has become overtouristed by Rick Steves devotees.