As far as appearance goes, it would be a matter of personal taste, as others have already indicated.

I, too, personally like the look of a 17" wheel filling the wheelwells of a DC2.

I (still) have both.

Quick reviews:
16x7 +50mm 215x45x16: Slightly firmer ride than 15x6 stock. Great grip in corners, slower steering response, my lightest/quickest combination. Currently on car.
17x7 +38 205x40x17: Even more firm, still comfortable ride, quick turn in and steering response, causes porpoising on stock suspension, scary in heavy rain/standing water.

I think the 17" stands out more (purely subjective), but could probably use a tuned suspension, as opposed to being on a stock car.

If I keep this car, I'll probably buy another set of wheels. I'm thinking lightweight 17" modular wheels.

But, the 16's do take off way quicker than my 17's and feel better all around (again, purely subjective on my part).

Have fun deciding!