I'm considering bringing a friend to Geneva on Sunday for a day trip. Does anyone know what the city is like on Sunday with all the shops closed? Are there people around or is the centre dead? Any tips on things to do?

Sunday will be a cold and raining day.
And yes, all the shops are closed.

I have to say I would think twice about doing such a long train journey when there won't be much to do at the end of it. It's not as if the train ride itself will supply much in the way of stunning scenery. It's a long way to come and the city centre will be pretty dead at this time of year, especially if the weather is as forecasted. There won't be much atmosphere - it's much better to come in Spring/Summer when there's more life out and about in the streets and you can lunch/ have a drink outside. I like Geneva but the town centre is a pretty small place and you need it open and the weather on your side to see the town and it's lake at their best.