Hey Scotttyd,

There are two different options for train connections with LH in Germany:

1. Rail & Fly
You book a flight into FRA and then add a Rail & Fly booking (you can do that online during the booking process or later). Your rail portion is priced as a fixed price of either EUR 30 (2nd class) or EUR 60 (1st class) irrespective of your train destination. You can use all trains on the day of arrival or the following day without having to rebook, just board the train you want. Obviously you will not have a reserved seat, but you can reserve a seat separately with Deutsche Bahn.
You pick up your luggage in FRA not at the general baggage belt but at the Rail terminal closer to the actual rail tracks. In terms of time you need for the connection: Walking from immigration to the train tracks takes about 15-20 minutes. I have no recent experience with how much time luggage delivery takes...
As you do not have a fixed train you are flexible and can even take an earlier train if your incoming flight is early (which happens frequently with the US flights). You will not collect FF miles for the train leg.

2. Train ticket as part of your "flight" booking
Here you book the train leg as a fixed portion of your ticket with a specific train, a "flight" number and a seat reservation. The class of travel depends on your ticket (eco and eco+ are 2nd class, Business and First are 1st class). You cannot just change the class of travel in the train. You pay as part of your overall ticket price.
Luggage handling works the same way as in case 1: you pick it up at the Rail terminal. In case your flight (or luggage delivery) get delayed you have to be re-booked to a later train. LH sells train connections with at least 1hr connection time. You will collect FF miles for the train leg.

Personally, I prefer the Rail & Fly option. It is flexible and you can travel 1st class for just 60 EUR anywhere in Germany, which is cheap.

Have safe travels

Primenumber