Congrats on the CJO. I was in the same position as you just a few months ago. If given the choice I was going to bid for the 757, but with a SSN last 4 starting with a 3 also, I was assigned the 300. Since I was assigned and not given a choice, was told that during the next bid I could bid what I want without any seat lock if I wanted to lateral or move down. (At least this is what I think I heard). I plan to just stay put for a few reasons. First I have no desire to go through the schoolhouse twice during my first year. Also looking at the 300 bid pack and the reserve lines this month...With the new class that just started I almost have enough below that I may be able to hold a line by summer. A crappy line, but a line. Movement looks like it will be fast. Of course with the upcoming bid, it all could change.

Bottom line, it is good to think about seat assignment but you may not even have a choice.