i have a fatboy that i will be adding spoked rims and new tires to. i was considering white walls for it but didn't want to mess with cleaning them. it sounds like it wouldn't be too bad after all.
I have wide whitewalls on my Roadstar, and will get them for my FLSTC when replacements are needed.
One downside to whitewalls is long distance riding. Two friends ride 30,000kms plus per year and they sometimes have to buy repacement tires on the road. The HD dealerships always seem to have blackwalls in stock, but IMHO, not always whitewalls. Thus, you could be forced into buying a blackwall if you want to get back on the road in reasonable time.