In reply to Blue Straggler:
Thanks for replies so far. With respect to the other suggestions, I think this may come down to a flip of the coin for Rome vs Venice. I think there will be future trips to Florence, looks like maybe 2 per year but I am not guaranteed to be on all of them (the work is just doing 2 presentations to a class of young professionals, basically 2.5 hours of Powerpoint from a standard existing presentation) so maybe I can look at Bologna, Pisa, San Gimignano some other time
It's funny that I mentioned via ferrata in the OP on a forum frequented by climbers and nobody has referred to it yet :-D actually whilst driving into work today I was expecting to check this thread and find a lot of people saying "why wander around any old city when there is via ferrata not so far away"
but it seems that ice cream, coffee, dirty pigeons and selfies are the way forward!
I was initially thinking of flying into Florence (flights from London City, for example) and out of Rome or Venice.
Maybe I can do some crazy "fly into Rome, see it for an afternoon, blast up to Florence on a late evening train, sleep, do presentation, see Florence in the afternoon and evening, sleep, get early train to Venice, see Venice, sleep, go home on the Sunday" :-o