I have about 5 IBM Model M keyboards. I have converted all of them to Dvorak layout, I would like my keyboards to all be completely blank ... however, I have a feeling that spray paint would wear out. And buying blank key caps for the Model M is pricy.
I'd recommend buying surplus model M keyboards from Ebay. You can usually get them for under $40 there. Otherwise there are places that will sell them new, but they go for around $100 to $120.
The tactile feel is great.
There are no stupid windows keys.
The clicky noise can be a bit annoying at times, however, I've gotten used to it, as have my co-workers in the cubes near me at work.
I plan on sticking with Model M keyboards for the remainder of my life.