Depends on your time. If your talking about a 1-3 hour stop-over I wouldn't venture too far, The Great Southern on the airport grounds provides a reasonible menu, not special though, if not the "Coachmans" just off the airport grounds, does a half decent carvery. Another option would be the recently opened Crown Plaza hotel in santry, no more than a 10 minute taxi ride, and a pleasant menu choice.
I would have to agree with the other posts here, for a 3 or more hour stop, I would suggest either Swords or Malahide. Both will have resteraunts covering all ranges, and both towns have their individual "Greats". Personel favourite would be Oscor Taylors in Malahide, wonderful carvery downstairs, and a lovely restaurant upstairs. Taxi cost would be about 22-24 euro return. If taxi fare is a consideration, then i'd agree with skyrabbit of the old school house.
The choice is yours
S.C.