Turin Airport: The sensible public-transport route is the airport train/bus into Torino Porta Susa, then the SAVDA bus to Aosta (about 2 hours from Turin). Allow roughly 2½–3 hours airport-to-Aosta and about €25–35 total, depending on the airport leg and fare. Aosta’s own airport is for private aviation, not a useful scheduled-flight gateway.
Turin Porta Susa / Porta Nuova: SAVDA runs several direct buses daily to Aosta, taking about 2 hours. It is often simpler than the rail route if you have luggage. By train, go via Ivrea: the Aosta–Ivrea leg takes about 80 minutes and usually involves a connection onward to Turin.
Aosta railway station: The station is immediately south of the historic centre: walk to Via Sant’Anselmo/Porta Praetoria in roughly 10 minutes. It is a regional terminus, not a high-speed hub; trains run hourly toward Ivrea, with onward connections for Turin and a change at Chivasso for Milan.
Milan Bergamo Orio al Serio Airport: A direct long-distance coach is the practical option when its timetable fits; Itabus advertises Aosta–Orio al Serio fares from about €23. Expect roughly 3–4 hours in real life. Do not choose Bergamo solely because the airfare is cheap if your arrival time misses the limited coach departures.
Geneva Airport: Geneva is geographically tempting but not frictionless: onward travel reaches Aosta via the Mont Blanc Tunnel and is generally best done by pre-booked transfer/car rental or a carefully timed rail/bus combination via Martigny. Allow at least 3–4 hours door to door; it is not an airport-shuttle city break transfer.