Lyon airport, also known as Saint Exupéry, is about 100 km away (1 h by bus, car or train). Busses go hourly to Grenoble. 22€ one-way, or 33€ return (valid for 2 months) ticket.
Geneva Airport, 157 km from Grenoble, is a common destination of many airlines companies. From the airport :
- Grenoble can be reached by car in 1H30 mns.
- By train (several times daily) it takes about 2 hours; the price is 23.60€ full price. If the train goes through Lyon, it is both more longer and more expensive.
- There are also direct busses to Grenoble for 57€.
Remember that Geneva is a Swiss city and depending on your country of origin you may need a visa. Since 2008 Switzerland is part of the Schengen area. European Union citizens should not have problems travelling via Geneva. It is also worth remembering that Switzerland has its own currency (the Swiss Franc); nearly all retail outlets in Geneva accept Euros but change is given in Swiss Francs. Geneva Airport also has a “French part” that does not require to enter into Swiss territory if you come from France and your destination flight is to France.
Grenoble Isère Airport, also known as St Geoirs, about 40 km from Grenoble, or about 35 minutes by coach. This is a small low-cost airport. Flights are more frequent in the ski season. EasyJet and Ryanair offer flights to/from Grenoble Isère Airport.
Several high speed trains (TGV) from SNCF link Paris to Grenoble directly every day, for a three-hour trip of 640 km. TER trains also link the city to Geneva in Switzerland (2h), to southern Alps (Gap, Sisteron) and to Valence (1h) where you can change for the TGV to Southern-France. More info on SNCF website.
See also Grenoble in wikitravel.