I think you're right, Nick
"Rigelkent", a.k.a. Rigel Kentaurus, a.k.a. Alpha 1 Centauri, (dec.~ -61 degrees) isn't visible in the part of Europe where modern astronomy was codified - and is as seasonal as Sirius where it is visible.
Vega is seasonal, too, but much less so for most of the mid-northern latitudes; at dec. ~ +39 degrees, it's almost circumpolar. I suspect color had a lot to do with it (spectral class A). Capella, at almost the same magnitude (0.08) and higher in the northern sky, is a G, like Sol.