I don't have the answer...but your wife does!
If you are trying to convince her to get into sailing then a fun week with a great charter crew is the way to go. They'll be happy to give you some instruction along the way. You can do the formal training later if she buys into the whole thing.
If she is sold on the whole idea from the start then I'd go the formal week of training. You'll still have fun (hopefully!).
Remember those 2 very important words...'yes dear'.