Alex,
I am also going to Geneva fo Ebace in May! – I did the show last year and it was very good. Geneva has a open terrace but there is a glass/perspex screen that you shoot through. Depending on landing direction it is easy to get shots of aircraft on approach – just turn right as you come out of the terminal and keep walking. Another place is outside the exhibition building itself – lasy year there were 4 helicopters parked outside.