My experience with BR in a parcel from Andrew: Excellent! Andrew packs his plants very well!!
Personally: I like ordering plants bare root / rhizome - easier to ship, and I like dealing with rhizomes vs. getting a plant with pitchers that could be damaged during shipping. I'd rather grow it my self. I try to order bare-root as much as I can, but then again, it is just my personal preference.
BR is bare root which means the plant by itself. I assume you know that, just typed your sentence wrong ;-)
All the Sarracenia are bare root and are just starting to wake up (most have flowers starting) so this is the best time to get them. Much longer and they'll have growth which means the cost of shipping goes up and likely the cost of the plants will go up some too. You also risk damage to the plant during shipping (and if the plant starts growing in your environment there is barely any acclimation to be done...)
As far as the Venus flytraps go, if you are comfortable with potting them up (they really are easy and very forgiving!) that's the way I would go. Again, there is less risk to the plant this way (it is easier to secure a bare root plant than potted plants) but either way I guarantee great plants. And of course, cheaper that way!
As far as which Sarracenia will grow best, I think they'll all do equally well there... I don't think any of the ones I have are going to be much pickier than another. So just pick something that looks good I don't have pictures listed for all of them, but you can look some up at http://www.humboldt.edu/~rrz7001/Sarracenia.html If I have any when they put out pitchers I'll make sure to get pictures of them for the store as time goes by.
Thanks for looking and hope that helps