M.6.
I like the idea of giving an "experience" rather than a gift. When my brother got married earlier this year, I got him and his new wife a "foodies on foot tour". What about day trips to a local vineyard, a pass to a local museum or orchestra group, anything that allows them to spend time together. I am not a big fan of gift certificates just to go out to eat, though, unless it is the place where they met or has some other special meaning.
Sometimes I check out TripAdvisor and look at the top 10 things to do for the town that the person or couple that I am buying for lives in for ideas.
Good luck!