I'm normally in Sen lounge in A. It's nice but really small and often overcrowded.

The Business lounge in C has recently been renovated. It's very large, and quite nice.
Sometimes when I overnight at the airport I cross back over to this lounge to check my email and have a drink. Only problem is that it closes early in the evening. I think 9 PM.

I prefer the VIE lounges to the FRA ones anytime. I've never looked for the showers there.

Enjoy.

Shofar