I agree with Stuey's point, you can try lots of colours or even better take a side on pic and use Photshop to go through all the colour choices.
MY 126 which is red has currently got white powdercoated 13 inch rims which really suit the look of the car (create a nice sporty contrast against the solid red colour). However my new rims are split rims (from Braid spain) and are gold powdercoated centres with polished rims which will give my car a differnt look again.
I you went for a bright blue of some kind and added a matching bonnet/roof stripe and maybe a side stripe to match in might look nice.
cheers Doug