St Goar vs Bacharach vs ??

What is your transport after you arrive at Hahn? It is not clear from your post, but sounds like you are renting a car. So that brings up the question, where will you drop the car after you pick up your husband?

Sorry for misleading you...

I will be on foot. I had not planned for a rental car. Flying Ryanair has its challenges I am told.

I have noted in RS tour book that there are busses from airport to Mainz. I thought I'd then find a train to ...somewhere lovely from there.

Tonya: They are both lovely; although we preferred Bacharach. Bacharach is smaller and we felt it was more quaint and lovely. If you are meeting your husband at the Frankfurt airport in the morning, you should have sufficient time to get him back to Bacharach, do a cruise to St. Goar (RS tour book has the information), take the train back (hourly departures at :19 minutes past the hour--get there a few minutes ahead to buy your ticket from a machine (cost is 3.80 Euros per person)) , have a great meal in Bacharach with ample German beer, and then drift off for 12 hours to get over the jet lag. There are plenty of trains from Bacharach to Trier (by way of Koblenz) that will get you to Trier in time. Go to http://www.bahn.com/ for the schedule. Good luck and have a wonderful time!

I would need to know your travel dates/days of the week to provide specific logistical advice.

Which town... both are about the same size and are separated by 10 train minutes, with Bacharach further south,. On most days there are direct trains every two hours between FRA and Bacharach with other options requiring a change of train in between. St. Goar has frequent train service as well but you will normally need to change trains to get to FRA. A minor consideration really unless you're disabled or carrying way too many bags.

In a nutshell: Bacharach has the most attractive old-world buildings (but also more noise than other towns from the passing trains.) St. Goar's buildings are less impressive, but it offers several other important advantages. Its location 10 minutes north of Bacharach by train is more scenic. St. Goar is also better for outings by train and for river cruising. If you're lodged in St. Goar, Rheinfels Castle (which is right in town) can be visited whenever it is convenient rather than having to make a special trip there. Also: a ferry in St. Goar runs all day long and allows you to access the east bank trains for trips to Marksburg Castle in Braubach or Rüdesheim to the south (if you stay in Bacharach you'll need to travel to St. Goar by train first.)

St, Goar Ferry and view from the St. Goar river bank: http://www.schiffbilder.de/1024/personen-fahrzeugfaehre-loreley-vi-zwischen-18381.jpg

So for your independent stay St. Goar makes a little more sense to me, all things considered. You might find it interesting to switch to a Bacharach hotel after picking up your husband at FRA (drop your own bags at the Bacharach establishment on your way to FRA??) Check reviews for comments about train noise.

You might also consider staying in Cochem on the more peaceful Mosel River instead of the Rhine. Trier is nothing at all like Cochem.

http://www.der-takt.de/typo3temp/_processed_/csm_NEU_T_Reichsburg_Cochem_3_087e83a8d1.jpg

Hahn shuttle buses also server Koblenz and Bullay, just upstream from Cochem.

"...you should have sufficient time to get him back to Bacharach, do a cruise to St. Goar (RS tour book has the information), take the train back..."

IMO this is not the best plan; Bacharach to St, Goar is only a 40-minute cruise and covers only HALF the most scenic segment, which actually begins in Bingen. Here's a map of the scenic part:
http://www.bingen-ruedesheimer.com/images/map/rhine-valley290.jpg
If you stay in St. Goar, then on the morning of your departure for Trier, you can take the train to Bingen, cruise back to St. Goar, and see the whole thing by 11 am. Then fetch your bags and head to Trier or spend a little in St. Goar first. Normally there's a train from St. Goar at around 11:30 that gets you to Cochem a little after 2 pm.

If you stay in Bacharach, you will be within the Rhein-Main Verkehrsverbund (Transit District) for trips to Frankfurt. When you go to FRA to pick up your husband, you can buy a single group day ticket from the vending machine. The cost is 34.50 euro. That will cover you to the airport, then the return for both you and your husband. The normal fare each way is 11.80 euro. Although this will save you only 0.90 euro, it will save time buying return tickets for both you and your husband for the return trip. Write both your names on the back of the ticket.

Because your route is in the district, the Deutsche Bahn website will not show the prices, but it will show the schedule. For prices, go to http://www.rmv.de/en/, this also has a schedule application.

To get to Trier, you can buy a Rhineland Pfalz Ticket for 2 people for 29 euro. Travel after 9 am on weekdays or anytime weekends. Again, write your names on the ticket. Then, you can hop on and off on the way to Trier if you would like to do a bit of sight seeing during the trip. If you buy the ticket from the ticket window, you pay a 2 euro service fee.