I just wanted to follow up on this thread now that I'm back from Palma (sigh).

There is an IB lounge in FRA, Terminal 2. The IB flights leave from the first level (the BA flights are on the second level - so no chance of using their lounge)so that is where the lounge is. The lounge is alllllll the way down in no-mans-land, nearly at the end of the concourse. It is right next to an Air France lounge, right by the gates that IB uses for their flights.
The lounge was tiny, basically an oversized room, with drinks and peanuts and cookies. However, it was much more comfotable to sink into one of the lounge sofas than wait near the gate. By far the most interesting feature of the lounge was that there was NO BATHROOM! If one needs a restroom, they must leave the lounge.
The BCN lounge offered more in regards to space, comfort, snacks, and, a bathroom! We used the lounge right near baggage claim B.
As mentioned, there is no lounge in PMI.

I hope this info is helpful!