Thanks so far for the input! I have tried numerous other searches for different connections. When I do a search for BRU-WAS (code for all DC area airports), the options that do have connection at FRA, ZRH, GVA, YUL, MAN, & MUC all are without saver availability. There are a few options for LHR and ORD as well as one at VIE flying home on Austrian, but that would mean an even earlier departure from BRU.

As far as the differences in taxes go, connecting in LHR adds the UK Passenger Service Charge of $55.40 (based on connecting from short haul) offset by the lack of the $2.50 September 11th fee that the ORD flights have. So all in all, the biggest reason to prefer the ORD flight is the departure time from BRU, the extra $105 in taxes is secondary. But now that you're saying I'd have to recheck bags at ORD, that sounds like a bit of a pain.

So to clarify, on the ORD connecting flights: I'd pass through customs, collect my luggage, check in and check my luggage for the domestic flight, go through security, have time in the lounge, and then board the flight? However on the LHR connecting flights: I'd deboard go straight to the lounge (luggage would be loaded onto the next flight for me), and board the plane?