Guinness is a low alcohol beer so it has about the same calories as a lite beer, but of course is much more tasty! At the sports complex they can add a dt red bull to guinness over ice. AWESOME post work-out drink!
Most of the vacation weight gain is fluid retention due to a high salt diet. Provided you are not sucking down sugar 24/7 you can't do that much damage to yourself, especially if you take lots of walks or hit the gym. Plus Couples has real good portion control, those drinks are only 10 oz or so, much better than giving you a half gallon worth of margarita like bars do in the states