Which train station out of Frankfurt Airport is best for Interlaken?

Long Distance:) It's a 4.5 hour journey and requires a change in Mannheim. You can check schedules at the Swiss Rail website www.sbb.ch/en

Although you could go all the way from FRA to Switzerland via regional trains, you probably don't want to. The best place to catch a long distance (Fern) train would be at the Fernbahnhof. However, if you just go out to the Fernbahnhof and look for a train marked "Interlaken" you're not going to find one. You will have to make a connection somewhere, and that information you will find on the German Rail query page.

It might also be possible to go from the Regionalbahnhof to Frankfurt Hbf, and then take an express train from there to Interlaken. You could find out that information on the Bahn query page, also.

Thanks, Lee (and Michael). I've gotten all the GE and SW railtables and schedules for departures from FRA via both regional (from airport and then out of Main Hbf)and Fern and both would work. However, I am still unsure which would be easier and more convenient, so will have to study them a bit more.

The fastest connections (just over 5 hrs) I found using the Bahn site were out of the Fernbahnhof with one change at either Mannheim or Basel.

As far as the easiest Bahnhof to use, probably the Fern. It is a ways out (10 min walk) from the terminal, but easy to get to. From Terminal 1, which is used by Lufthansa and most star-alliance airlines, go up to the 2nd floor mazzanine (on the left side of the building, facing the street), then across the sky bridge and out the hallway through the red-brick building across the street from the terminal.

If you try to go into the Hbf from the regionalbhf, which is under that red brick building, accessible from Terminal 1 through a passage way under the street, you will most likely take an S-Bahn into the Tief (underground) S-Bahn station under the Hbf and have to come up several flight to the main level of the station.

If you go to the Swiss Rail web site and enter the regional station instead of LD, it literally tells you to walk over to the LD station:)

Okay, guys, looks like I'll just go for the long-distance station (Fern) and be done with it. Makes sense. Now since I just found out about Fern, I need to tweak my connections a bit out of Interlaken for Lauterbrunnen. Thanks again!

The connections from Interlaken Ost to Laurtebrunnen are always timed with the intercity trains; so you shouldn't have to wait more than 10-15 minutes. Your best option is to simply take the morning train with one change in mannheim to interlaken . Once you arrive at Interlaken Ost the train to Lauterbrunnen will be waiting across the platform.

Michael, I'm thinking my Eurailpass won't get me on a local Swiss train and I'll need to get a ticket to Lauterbrunnen, right?

Eurailpass gets you a 25% discount past Interlaken.
You may want to consider purchasing a Swiss Half-fare card or BO pass once you arrive in Interaken.You can get full details at the "railpasses" section of this website.