I was in the BCN lounge on Tuesday.
BA uses the Joan Miro lounge, so a shared third party offering.
There is a reasonable selection of drinks, including Cava and premium brand spirits. There are also two fridges with good selection of soft drinks and beer and a coffee machine.
Beside crisps and nuts, they offer sandwiches, rolls and pre-packed salads. There is also a freeze with a selection of ices creams (a rarity in lounges).
Wifi has to be paid for, but there are a some computers that you can use for free (if you can get on).
Lounge has a number of quiet rooms/resting areas.
This was my third visit in six months - each time the lounge has been about half full at most.
I hope that helps.