as someone who actually runs 19's with "ricey" stretched low profile tires, don't knock it til you try it.IMHO it's too much wheel, it looks awkward on the car and means you need to run very low profile rubber which a) looks a bit ricey and b) butchers the ride which is already mediocre at best.
I'd ideally run 225/50/18 or 235/45/18 but the former is a tad too much diameter.
no real difference in the ride, the difference that is there, the average person wouldnt notice. i drive through a city pretty regularly (phila.) just dont be a dumb *** and keep an eye out for potholes, even outside of city.
most of these post are personal preference and not personal experience. half of these guys are still running the stock 17's or 16's and arnt even running aftermarket wheels. you want to take a look or post in the "aftermarket wheel gallery" sticky for some real feedback. while 18'' is the most common choice, there are 19's and even 20's being run on 93's.
TLDR: you can run 19's perfectly fine, plus it's you car and your money, go for it.