Vantagebox,

In order to address you question about connecting in FRA we would need some more info. What airline are you connecting to and is your connection flight to a EU destination ? If you are transiting through FRA and NOT connecting to the EU, you do not need to go thru immigration nor security.

As to the arrivals lounge... United closed it's Red Carpet Club in FRA last October (2009). Your profile does not indicate whether you are a Star Alliance Gold member such as United Mileage Plus Premier or 1K. If you are a Star Alliance Gold member, you can use the Lufthansa Business lounge which does have showers. However, they are usually very crowded and the waits for a shower can easily exceed an hour. Also, you did not indicate if your connecting flight is in F on a Star Alliance carrier. If so, you might be able to use the Lufthansa First Class Lounge. This is one of the nicest lounges around and you will have a very short wait, if any, for a shower. If you are connecting to a Lufthansa First Class flight, they will drive you from the First Lounge to your flight.

The length of time you have should be enough to get a shower unless you are connecting to an EU destination.

Have a great flight !!