I can only speak to the appearance.
I think spokes look really good on the xB, I chose the TSW Nurburgrings in 18" x 8" wide. I have a Black Sand Pearl and I've always been a fan of the darker colored wheels trend.
When these arrived they were way lighter in color than I imagined and pictured online. The color scale goes Gunmetal (lightest), Athracite, Charcoal, Black. All of these colors look good in my opinion, but with black, someone made the point that it could be confused for steelies without hubcaps. Silver cars look particularly good with dark wheels, and the newest trend I've seen is bright color cars with white wheels. I'll admit I like that look a lot too. For black cars, gold is an option, I'm not sure about other colors. For an example of gunmetal, see my wheels, for an example of athracite see BrickPig's
(I think - not sure), and for an example of charcoal wheels, see Ronin's
. Those are just kind of my take on the three colors, not official or anything.
If I had to do it again, I would take a more serious look at the "mirror face" gunmetal wheels - they're trippy, they seem like chrome unless viewed at an angle, then they're grey. I would also look at wheels with a chrome lip because that can look pretty classy. Lastly I really like these BBS wheels, any color: