My preferred Senator lounge is the "Term A, level 3, gate A51" because it tends to be less busy.

However, I don't think that anybody will really enjoy any of the FRA LH lounges.

Whenever the time permits I go the UA RCC close to gate C2. It's a bit of a hike but I find it ten times better than the LH lounges. Less people, less smoke, better chairs and better food/drinks.

I would never extend my stay at FRA in order to "enjoy" myself.