I took a cruise from Rudesheim to Koblenz with my grandparents one summer and there are three things that I remember very 
clearly: craning my neck up at the Loreley Cliff face, walking through a winery slightly tipsy despite a belly-full of potatoes, and my Opa (grandfather) wrapping a shawl around his head and speaking Arabic on the top deck of the boat.
There are several companies that offer tours of the Middle Rhine Valley, most of them visiting one or two of the more famous castles along the way — Marksburg or Ehrenbreitstein for example — and stopping along the way to sample some of the Rheingau’s famous wines. This section of the river is known as the Romantic Rhine and if you have a free summer and a significant other on your arm, a week on a boat between Koblenz and Rudesheim can provide you with your own wine-soaked memories.
My Opa is a big history buff and he felt that one or two castles and an afternoon drinking wine was insufficient, so we ended up disembarking and taking our own tour of the castles that involved a lot of walking and talking. I would recommend this for anyone with the time to do so. There are more than 40 different castles, estates and fortresses along this stretch of the Rhine and at least as many 
vineyards with attached restaurants serving up steak and schnitzel, and there is not a single tour out there that can do them all justice.
You know, it is possible to hike all the way from Koblenz to Rudesheim.
If you are driving, you might consider parking in some tiny little village, perhaps a place like Niederheimbach, and then walking a bit to the nearby ferry and crossing the river into Lornhausen and staying a night after a huge meal of meat and potatoes.
Maybe you would rather drive straight up to the Lorelely Cliff, look out over the river toward St. Goarshausen, then park and keep heading north — take the ferry part of the way, drive a little more of the way, walk another bit of it; double back and visit a bed and breakfast that may have caught your eye.
Every single castle (or ruin of an old castle) has a museum telling the history of that particular edifice. Most of the time the museum is tucked away on the castle grounds, usually next to the gift shop, and you can slowly browse the many picture books and outright historical treatises (in many languages). Hopefully, you will come across museums that are locked away in some old man’s head and you will have to pry it out of there with well-placed orders of local wine.
Written by Sascha Matuszak for EuropeUpClose.com
For information on River Cruises on the Rhine contact our sister site Euro Escapes