Helsinki
In the international departures area, just befor you go through the second check to the non-Schengen gates (so say gate 29), up a set of stairs but looking over the gate area below, there's a pleasant full service restaurant (which is relatively unusual in Finland overall). Usually quiet.
Prague
Once again up a level from the main area, between the two piers, right by the little outside spectators area.
It looks a bit like a school lunch canteen but has lots of interesting hot Czech dishes, the sort of thing I always find great when in transit. They take Euros. And the cashier spotted I had chosen (quite inadvertently) non-alcoholic beer and in quite adequate English sent me back for some "proper Czech" stuff !