And does anyone think they would look good on the car?

JAGUAR XKR "JUPITER" 19 INCH CHROME WHEEL EXCHANGE XK-R | eBay

 

I like those! They might be to modern of a style though....a quick Photoshop should give you an idea

 

Look good to me except I could never live with chrome even if I liked it.
Looks like a natural progression of the stock wheels.

What does the bigger rim look like with the smaller rotor though?

 

I emailed this exact selling asking if I could trade in my STR wheels for a set of chrome 19s or 20s. He told me no, will only exhange the same wheel. Keep in mind this is a chrome EXCHANGE, the buy it now price is assuming you send back your wheels AND they're in near-perfect condition. They charge a $1600 core + ebay buy it now price + shipping when you buy, then when you ship your core exchange wheels back (at your expense) they will refund UP TO $1600 but deduct any wheels that aren't near perfect.