I took my 94 Sailfish out yesterday after three weekends of bluefin tuna fishing on a friends 96 Marlin. The first thought when I got back on my Sailfish was "Who shrunk the boat?" They are practically carbon copies of each other except for the size and where it is the most noticeable is in the beam.
Younger, thinner folks (or newlyweds) will disagree but he V-birth area of the Sailfish really only sleeps one comfortably and my wife gets that when we overnight. I sleep in the mid berth. The Marlin's mid berth is both longer and wider then the Sailfish's and the V-birth is correspondingly larger as well. However, the differences are not "night and day." I suspect you will be uncomfortable on either boat after a whole week so the question will be how much discomfort are you willing to put up with when weighed against the other features of the two models.
As long as I have an open invitation on my buddies Marlin to scratch my tuna itch, I'm happy with my Sailfish for the time being. For one thing, his Marlin uses perhaps as much as 50% more fuel than my Sailfish. I watch the fuel burn rate with his old-tech 2-strokes and he barely gets 1MPG. Sometimes I see 1.1 but just as frequently see .8 or .9. The Marlin ride is much more comfortable - it's more of a plower then a banger. It is a bit slower than the Sailfish, however - mine screams at 48 MPH. I occasionally fish solo and can easily handle the Sailfish by myself when docking (except when there is a crowd watching :?) My buddies Marlin has a bow thruster so it is very easy to dock but without that, it may be a bit more of a challenge to dock solo (although I'm sure guys here do it.)