A bit of a late contribution... but I'm about to do exactly this on a pair of 28" Westwood rim wheels I've just got hold of for an old Roadster. I'll be using brush on satin black Rustoleum.
I've done this before with a 26" wheel sports roadster using bright red paint, and the wheels looked fab, though there are now some nice black "thick pinstripes" from the brake blocks!
If the budget will allow, I'd second powder coating as the best solution.