River and lake boats along the way

We've been on several "tours" on various lakes /rivers. They were not so much a tour as just transportation from one place to another, even though some were round trips and some were loop trips. We never found them to be so crowded that we needed to buy tickets in advance. Not doing so also maintains the flexibility of your travel plans to adapt to weather and other changes that might come up.

These are all just turn-up-and-go trips. There are often multiple operators in the same spot. Just pick one you fancy and go on it.

Check to see if your rail pass covers the little tour boats on the Lake Geneva (which they call Lac Lamon) Ours did but our cousins paid for it in their haste to get us aboard. Sometimes you can plan ahead to enjoy a seated meal with reservations but also their are sandwiches and snacks available without reservations. It was a pleasant journey on the boat as we sat on benches looking out at the hotels, and vineyards from Lausanne to Vevey and on toward Chateau Chillon. I would just wing it and go with the flow. LS

You won't need reservations in advance for any of those anticipated boat rides. As pointed out earlier, if you have a rail pass, the Rhine River trip may be included in the price of your rail pass. Just pick a lovely top deck seat and sit back and enjoy the scenery.

You're awesome with your timely responses. Thank you so much. I will do as suggested and just go with the flow. As for now, my mind is settled. Auf Wiedersehen

Both K-D Line Rhine & Mosel boats and most Swiss Lake boats are just offering discounts to Eurail pass travelers, instead of full coverage, but do show a pass at ticket windows as you go, since offers vary. In Switzerland, Swiss Travel Pass also has different offers from Eurail-brand (multi-country) passes.

Just show up for the Rhine trip. Do consider a longer ride than just 30 min. Otherwise, why even bother? Ride from Rüdesheim or Bingen up to Boppard or at least St. Goar. Show your train ticket for 20% off your ship ticket.