Knight And Day is goofy and reasonably fun, and Cruise is fine in it. It's basically a knockoff Mission Impossible crossed with It Happened One Night or something.
I haven't seen Far And Away, but I like what David Thomson says about it in the introduction to his book about Nicole Kidman:
So, I will be gentle and tender on passing over some things. If I elect to say little about the movie "Far And Away", for instance, then understand that the people involved were in love. It is their business. Sometimes it ends up looking like "Pierrot Le Fou" or an Ingmar Bergman picture. Sometimes it's "Far And Away" - enough said.