OOS and regular decision: one B in 9th grade AP US Gov, one B in 12th grade AP Calc BC. 4.6 wGPA, 11 APs, half with exam scores of 4 and 5. 35 ACT.
I think the B is less important than for what class it was. We were told not to worry about her grades in AP Calc BC, since she wanted to major in international relations, not STEM, and it's one of the most difficult APs (in retrospect she should have taken AP Stats!). If the overall rigor of the profile is high, then a B here and there won't matter so much.
DCUM also says W&M appreciates demonstrated interest, but we didn't visit or interview before she applied literally the day of the RD deadline. Maybe it matters more if you're in-state and the profile is a bit weak to begin with.