GVA airport is 6 minutes from downtown by train (5x an hour), 20min by bus or taxi given the ongoing construction work. I recommend the train.

The most popular sights in Geneva are:
- the 'jet d'eau', which is the 300+ft tall fountain on the lake
- the lakeside (5-10 min. walk from the station)
- the old town and its St. Pierre cathedral (10-15 min. walk from the lakeside)
- the left bank shopping streets, e.g. upscale Rue du Rhône (2 min. from lakeside)
- the international organizations (UN, ILO, WHO, IRC, etc.)
- boat ride on lake Geneva, various durations from 1hr up.

Geneva is a small town, and all the sights (except the international organizations) can be done on foot in half a day.

My recommendation is to take the train to the main station, head straight for the lake down rue du Mt.Blanc, stroll on the lakeside (option: can walk north on either bank for a good hour, quite scenic), go up to the old town, go down the other side to the university's grounds (Parc des Bastions) and come back to the station by way of the shopping district. There are plenty of eateries on this course, which can be done in two hours not counting stops.

There used to be convenient pink-painted bicycles which anybody could use for free, but their numbers have dwindled due to abuse and disrepair. A rental bicycle would be ideal to view the lakeside.

The local museums are not world-class.


Alternatively, there are a number of easy, scenic day trips which can be done from Geneva by train: Nyon, Rolle, (20min), Montreux, and the quaint villages in the wine-growing area between Lausanne and Montreux (e.g. Cully, Epesses; require a change of trains in Lausanne, about 1hr total)