My sense of smell usually has me stopping eating any passenger-meals
Vb was recently adjusted on the 737 PG from M.70 to M.73
I always thought M.70 was a bit low.
I normally slow down to
Vb in moderate turb, when the speed starts to jump up and down. In the 737 NG this tends to happen sooner then on the PG. Both because the speed indicator is more jumpy and because econ cruise speeds on the NG are much closer to MMO.