It will really all depend on what you want to do with it,
But here is what i was thinking.
If you goto a 14" or 15" you can run bigger brakes.
Then you can use the Sigma Front suspension and brake disks and calipers which is a very common upgrade.
15" is a very common size, so you can you can find rims and get tyres really easily.
If you run a lower profile tyre that will allow for your Outside Diameter to match the stock OD,
so it will keep your Speedo matched.
And lower profile tyres will help handling and they look good.
But check what is the biggest you are legally allowed to go over size from the factory Wheel Diameter with out having to get an engineers approval in your area (state/Country), becasue that may be a factor to allow for, money wise and legality wise...
But if you want to keep it stock, a nice set of 13s will look really cool also
Just some ideas
Hope this helps at all