This is very last minute planning for later this month.
I am planning on going with my father to Siegburg outside of Bonn in an effort to research our family's genealogy, or worst case, simply to walk along the same streets as our ancestors. We can trace our family back to Siegburg at which point the trail runs cold and we plan on visiting a local cemetery or two in an effort to locate missing relatives, and to simply admire the town my ancestors abandoned for the US. After that, historical enjoyment on the way back to Frankfurt. The bonus is that my 68 year old father has never been outside the US, so I would like to introduce him more to the world of travel. (I've not been to Germany yet.) I'm looking for a good "wow" factor for him to entice him to travel more.
As an airline employee, my dates and exact length of stay are very flexible.
My very rough outline so far is:
Day 1: Fly into Frankfurt in the morning, ICE train to Siegburg, rest.
Day 2: Explore Siegburg and hopefully our family history.
Day 3: Train to Cologne, quick visit to the cathedral, then train to the Rhine via Koblenz. (The cathedral can certainly be optional if it interferes too much with getting to the Rhine.)
Day 3-??: Exploring the Rhine Valley.
Last Day: Fly home from Frankfurt.
So I'm mostly looking for a good itinerary for exploring the Rhine southbound from Cologne or Siegburg. My initial thoughts were train to Boppard, boat to St Goar, train to Bacharach. Obviously that is too much in one day from Siegburg via Cologne so I'm trying to figure out a logical way to break it up. I would think grand total 7 days maximum in Germany. My father is 68 and still quite mobile but not as quick to keep up anymore. His primary goal is seeing "old buildings and nothing modern." Fair enough.
A German friend was telling my father about Old Town Cologne so he wants to go there, though I think he would be more impressed with an extra day on the Rhine. Just my opinion. But maybe I need to budget a night in Cologne before heading down (up?) the Rhine.
Any help on a father-son trip southbound on the Rhine would be appreciated.