Personally, i wouldnt want to do a 19" and above anymore. I regretted changing to 19 but no choice now stuck with it and cost a bit of money to get out from it.
18" would be perfect, a mix of a bit garang, better handling and a little bit cost effective.
I find that for a 19" it doesnt really affect you much on comfort (of course i can bear with it tats why i say so).
The reasons why 19" and above is troublesome is that when you run a compatabile set of tyres u r always on the alert on even small kerbs, etc.