I think all things considered Dan, 18"s are just about right. Aesthetics aside, I've weighed up many times and concluded that 19"s don't offer that much over 18"s in this country given our quality of roads, and tyre prices of course.
On a bigger car, 19"s appear the right thing but I guess you
pay for it.
Spacers and coilovers on the agenda? I think they'd suit this very well.
I also know a friend of a friend with the same colour as yours that's wrapped the grille in a gloss black (to match his gloss black wheels) and it looks very smart, very aggro too