I had the 27 game package in '08 and '09. I found it impossible to sell tickets to games I could not use. Also it became work to dedicate a whole weekend to baseball (I had weekend package) when the Sox were in town. I was paying for 3 seats and parking so it was kind of expensive.
That being said, it was cool to be a part of the Sox for that period of time. I have found the secondary markets work better for me now. I may pay a little extra for special games, but I have great seats (my seats were in sec 110, not good). Also if I want to go to a regular game at the last minute, I can pick up good seats for a fraction of the cost.
It is possible to find tickets for any perk at the park (grinder bash, stadium club, etc). I guess if you want to have the experience of being a part of the Sox family you should try it this year. Maybe the seat selection is better now than it was 5 years ago.