I too hope that there will be some better story lines in the next 2 movies, with the inclusion of characters like Ultra Magnus, Grimlock and Trypticon. I'd also like to see the story split over the two movies, Kill Bill style, with a semi major battle at the end of one (Autobots rescue Spike (call a spade a spade!) and a smaller Autobot from Trypticon in a skirmish led by Kup). The second movie could then focus on defeating Unicron with a plausible yet uneasy truce between Autobots and Decepticons.

And while I don't think you could kill off 'Bee, you could send him on a vital mission to the opposite end of the galaxy at the beginning of the first movie and have him return only in time for the final climactic battle at the end of the second movie. This limits him to only a few scenes on a space ship (millenium Falcon style) and maybe a space dogfight. This would give Hasbro the character development they're after as 'Bee contemplates his seclusion to deep space while the replacement characters on Earth get some solid screen time!

Sorry if I got a bit off topic, but I'd pay to see two movies along these lines and though I realize I may be a minority planet wide, I think Bay would probably be the best choice to successfully do this kind of plot line as a pair of live action movies.