I'm traveling with my wife, our 2.5 year old toddler and a lap infant on a round-trip from DCA and am considering buying BE despite the risk of not sitting together. Here are the reasons:

• Flight cost per person is only $130 vs. $280 for main cabin
• Flights are on E90s (so 2x2 with no middle seats)
• Flight is only 45 minutes long
• My wife and I don't need to sit together, however one of us does need to sit with the toddler and the other will hold the lap infant
• Tried this under similar circumstances on UA in BE and they "pre-assigned" us in 3 seats together in row 2 on a CRJ-200 (and then, in a cruel twist of fate, they kicked the 1K sitting next to us to the back of the plane for "weight and balance" issues)

I know many people think families buying BE is rude (because it's potentially burdening other passengers if they have to switch) but that burden generally involves middle seats. This plane has no middles and we'll happily take two seats in the last row (the "poop seats" next to the bathroom) as long as there are two together.

I understand we can still get 1 free checked bag each with the AA credit card, but I rarely fly AA. Are there any flaws in this strategy? If this were you, would you buy BE or main cabin?