Joey,
Let's throw another iron into the fire -- have you considered Regent (formerly Raddisson). I was very close to signing up with them for a 2005 trip, but had to scrub the trip because of a work-related conflict. I believe Regent has a no-tipping policy which it enforces! And, depending on the stateroom, they have more amenities. Also, I believe I read that the rooms are among the largest in the industry and the ships are small to mid-sized. I also believe their pricing can be competitive. When I checked they have a Transatlantic that is reasonably priced. At least worth looking into.
I have a neighbor who went on Oceanana this spring, but I can't go on their say-so alone (they always tend to have the "best" -- at least in their own minds. They did say that reservations in the alternative dining rooms was limited according to cabin category. And the food was "good" but not "great." However, I cannot vouch for their assessment.
As I prefer to bring my tux out of moth balls occasionally, I like a few formal evenings that X or Regent or many others offer, rather than all casual.
Of course, these are just my views and 3d-hand impressions, and I cannot voice a first-hand opinion on some of the alternatives.
Good luck on your planning.
Avie