For me, the price needs to be quite a bit lower to justify a layover even on pure financial grounds. I can't back this up with any hard math, but my sense is that time in transit curtails my productivity severely enough that there'd have to be a pretty enormous savings in ticket price to offset the cost of having me spend (say) twice as much time camping out in airport waiting areas and being subject to takeoff/landing laptop embargos.
I can't really point to a whole lot of productivity when traveling anyway. And, if I'm being honest, I will sometimes take connections to fly preferred (because of programs) airlines on longer flights. But, yeah, it's more time and that many more opportunities to have blown up travel plans that do lose significant chunks of time.
