In the main station ask for the Ländertickets or the Regio-tickets.
Such tickets can be used by a group of up to 5 persons in the RB, RE an S-Bahn trains as well as for local transport.
The Hauptbahnhof is also within easy walking distance of the inner city and several good hotels.
The closest airport with a good selection of international destinations, though much less frequent than the major airports Frankfurt (IATA: FRA) or Zürich (IATA: ZRH), is the Euroairport Basel/Mulhouse/Freiburg (IATA: EAP, IATA: BSL and IATA: MLH).
Buses run frequently from the airport to Freiburg; see the schedule here.
Freiburg im Breisgau is a major city in Baden-Württemberg in southwest Germany, situated on the edge of the Black Forest (Schwarzwald).
Picturesquely located on the river Dreisam, in between green mountainsides, it enjoys one of the sunniest and warmest climates among German cities.
They are a much cheaper alternative for a group of travelers going to cities nearby or going for a day trip.