Two suggestions.... Put fiberglass insulation in the joist bays in your basement (if you have one). Caulk the bottoms & tops of the baseboards. Both suggestions seem minor, but in my experience they made a pretty significant difference.

You might also call your local utility company and see if they offer low cost energy audits. Out gas & electric companies subsidize then here. If you can, see if you can get an infrared audit....it shows you exactly where the cold air is flowing and it's not always where youthink it is. It also is really cool :-)

Insulate the floor of your attic. Hot air rises and if the insulation is up there, the hot air stays on the 2nd floor.

Why didn't the blown-in insulation stop convection in the wall and seal the floor-to-wall joint?

That's a good question, mighyanvil, I was hoping that the blown insulation would have sealed that area.

I peered behind an outlet box on the second floor, and the insulation was well packed. That's about as close to an easy inspection "port" as I can get. Wish there was a way to see if the insulation actually sealed that rim joist opening on the exterior wall (sorry, I don't know what that area is technically called).

To clarify the original question, the concern isn't so much the temperature of the house, but that the second floor floor (the floor surface of the second floor) is frigid and that cold surface seems takes it toll on the comfort of the room.

We've taken measures to air seal the house, including using a small bead of clear caulk along the bottom edges of the exterior wall baseboards. Surprisingly, that area was one of the most in need.

Old western Pennsylvania farmhouses had fireplaces on the first floor, with open metal grates in the floor to allow heat to rise to the bedrooms. The one I'm most familiar with was retrofitted with a furnace sometime in the 20th century but the forced air only goes to the first floor. Again, the open metal grates are the chief source of heat.

Lots of blankets or quilts on the beds, and the second floor mostly used for sleeping.

Yes, that's just how our house was. The grates between the floor have been filled in, and the heating source/stove connection to the chimney on the first floor has been sealed. Luckily, the steam heating system was installed on both floors. And that's just how we're been living; with piles of blankets and not really enjoying the second floor rooms for anything else.

Sure would like to have warm floors, any suggestions are welcome. The conductivity of the cold through the floors is remarkable.