We are planning a trip in Sept and would appreciate help with figuring out how to use the train system for travel. We arrive in Frankfurt about 10:30 on Friday morning, have reservations in Boppard for 3 nights then we want to travel to Berlin on Monday morning. Thanks for the help.
If there are only two of you, you can purchase a Rheinland-Pfalz-Ticket for 27€ at an automat at the Regionalbhf at FRA plus local S-Bahn tickets to Mainz at 4,35€/adult, 8,70€ for two. That's 35,70€ for two. Or, you can just purchase Bahn tickets, from the automat or at the counter for 20,10€/adult or 40,20€ - a little more €, but less complicated. For three or more (up to 5, total) use the RL-P-Ticket.
FRA to Boppard by local train - as described - makes perfect sense.
From Boppard to Berlin, however, is a long haul and a little more difficult. Boppard will only be served by local trains (regional bahn). Since Berlin is a long way, you will want to transfer to something faster as soon as possible, presumably Koblenz. For that, I'd suggest checking out the Deutsch Bahn website early to buy some discounted tickets rather than wait to buy them at the station.
The responses to your question are good. Buy those tickets online ahead to get a cheaper rate.
Thanks for your help. This will be new to us, but it sounds pretty straight forward.