I must confess that I only went to Koblenz for a trip along the Rhine.
The views were gorgeous, but the trip was so problematic that I saw it in a rush.
I enjoyed it, and promise to return with time.
After having see the Deutsches Eck, walk to the side where you find the Mosel River. Here you have your most beautiful view of the old town of Koblenz. Walk along this river front to get back to the point where you began your walk--the Deutsche Kaiser. While walking along the Mosel, keep looking to your left for the 3 white slabs of concrete, which are pieces of the Berlin wall that were brought to Koblenz after the fall of the wall November 9, 1989. You have completed you walk of Koblenz!
Once you reach the Rhine, take a stroll along the river to enjoy the view of the Fortress Ehrenbreitstein. There are many souvenir kiosks here, selling postcards and the like. Also, there are many boats along this promende offering day trips along the Rhine. Some go Koblenz-Boppard, others Koblenz-St. Goarshausen, etc. I would recommend to do the full length of the Rhine gorge all the way to ruedesheim in a day, and then take a train back. this way you will get to see all of the castles (about 32 castles or castle ruins). I would then have dinner in Ruedesheim, though it is very touristy, you can get some great food like Rheinisches Sauerbraten (beef strips marinated in red wine vinegar), a specialty of the region. The you could take the train back to Koblenz, and then after having seen all of the castles from the boat, you could decide which ones to possibly visit. The Marksburg in Braubach is the only castle to have never been destroyed, and is great to tour, and also Castle Stlzenfels, very close to Koblenz would be great to see because it shows you the exact opposite of what you see at the Marksburg. marksburg is like a real castle--plain and medieval-like, the Stolzenfels is opulent and beautifuly furnished.
This is the Mosel waterfront. This runs just behind the old town and you can duck up anywhere along here to get into the main shopping and eating areas.
There was a little market going on along here too, but to be honest it was mostly tat.
Koblenz has two different waterfronts, one on the Rhine and one on the Mosel. The one by the Rhine gives nice views across the river to the fortress on the opposite bank, and the waterfront is lined with cafes, boat tour places, and shops selling postcards of Bavaria (????).
Walk along the Rheinanlagen, the river-promenade.
The walk takes you past the Weindorf (wine village) a relic of the wine-fair held in 1925. The walk ends with the formidable DEUTSCHE ECK an enormous momument erected for Kaiser Wilheim I in 1897 and is now dedicated to German unity. It displays a huge eagle disposing of 6 serpents and 2 human enemies. The 72foot monument is now a pedestal - the Kaiser's statue was knocked off in 1945 with the motto: 'Never will the Reich be destroyed if you are unified and loyal'. Climbing the 107 steps gives good views of the old town along the Mosel and the more modern construction along the Rhine.
Watching the River boats move along the Rhine River. I live by the Mississippi River in Illinois. And one thing that is fun is to just watch the boats along the Rivers. But you do not get this kind of view in Illinois.
Take a walk along the Rhine River in Kolbenz. This one of the monuments where the Mosselle and the Rhine Rivers meet.