if the exterior is vinyl siding, then the easiest path may very well be out through sheething, then down the outside of the house under the vinyl siding, then back in through the sheething on first floor. Biggest trick with this is popping out the siding so you don't drill through it.
In my house, I have my "head end" in the basement under the stairs, and needed to connect to OTA antenna in attic. I ran a 1 1/2 inch conduit down the chase next to the water heater flue (far enough away to avoid heat - and flue is double wall)
also, joists holding up first floor and second floor may very well not be the same. My home has I-beam style joists for first floor (easily seen from basement) while the second floor has truss style joists (which are definitely "taller") - figured this out while running the above described conduit.