I'd imagine your best bet would be a OW hub, if you want entry for pax departing to a variety of destinations.
HEL has a nice, fairly new premium lounge (OWS/OWE only) in the non-Schengen area with champagne and other wines and spirits as well. There's also a newly renovated Finnair lounge in the Schengen area, which serves sparkling wine and a variety of other wines and liquors. Both lounges are fairly quiet outside the morning and afternoon rush hours, and have decent food/snack offerings.
Only problem I can see is somewhat limited departures in the late evening.
How about MAD as well, it's been a while since I visited the Dali lounge but I heard the offering is quite good these days.