Layover in Geneva
 

I have about a 4.5 hour layover in Geneva on an upcoming flight. Is that time to see a bit of the city. If so any suggestions as I've never been to Switzerland before.

The train to the city centre takes 10 minutes and is free with the ticket that you pick up before going through customs. You'll be fine with about a 3-hour tour.

Walk down from the train station towards the lake and enjoy the view.
On the right side - as you are looking at the lake, past the bridge is the more commercial part of town; some nice shops and all in all a nice walk.
Geneva is very pricey but the lake is worth the train ride into town.

(Of course it's true anywhere but my friends who live in Geneva make a special point of reminding me every time I visit) Beware of pickpockets.

cheers,

Henry

As an alternative to the train, take the number 5 bus (the free ticket is also valid on this) and get off in Bel-Air. The trips is a little longer, but you'll see a little more, including the Place des Nations. Indeed you might even want to get off, look around and catch the next bus. From Bel-Air, walk up into the old town and explore a little, including the cathedral - pay for a walk up into the tower for a great view over the city.
Your outgoing ticket is only valid for 80 minutes, so you'll need to purchase a ticket (from any bus-stop, the machines work in English and take credit cards) to get back to the airport (easiest is a number 5 bus again, but there are other solutions depending on where you are).

What does it mean that the ticket is valid for only 80 minutes. Is that for the return as well. That's actually pretty nice that they have a free ticket.

Couple other questions:
- Are credit cards accepted regularly. I'd prefer not to get cash for such a short stay.
- How much time to give myself coming back through the airport (i.e. security lines, walk to the gate, etc.)

The free ticket is obtained in the luggage reclaim area, just before you go through customs. It gives you 80 minutes of unlimited travel on public transport (trains, buses, trams, boats) in the whole canton of Geneva, so it will allow you back to the airport if you do that within the 80 minutes.
Credit cards are pretty widely accepted these days, though some places won't accept them for small purchases below 20 CHF. There are two types of ticket machine in use at the moment in Geneva, the newer ones (with a touch screen) accept credit cards, even for small payments, though I cannot guarantee they will work with US credit cards (see other threads for problems that US travellers have with US credit cards).
Getting back to the airport, assuming you won't need to checkin, one hour is plenty of time, 45 minutes is probably OK. Unless you're at peak times, security won't be more than 10 minutes, even the most remote gates aren't more than 10 minutes away and if you're going outside Schengen, the passport control usually is only a few seconds. The airport is small.

If you're departing on the French side, it's very fast. The Swiss side can take a long time (I've spent over 45 minutes in the security line once - it was only once, but it can happen). The airport is small, but the security lines can take a long time. If you travel during ski season, expect long and very, very slow lines (think lots of kids).

to add my question
 

For a day in Geneva (later morning to late afternoon / early evening), from Gare Cornavin (that's where the train from the airport leaves you), is walking towards the lake, then across the Mont Blanc bridge, then on to the Old City a good itinerary?

Thank you for the suggestion about bus #5! Where is the Bel-Air station? Is that near the lake? I'd rather take the bus into the city than the train (because you can see more).

Bel-Air is the first stop after the bus crosses the Rhone river. To get to the old town walk upwards, until you can't go any higher. To get to the lake, follow the river, you can't really miss it from Bel-Air.