IMO I'd leave the grill alone. Black would be out of place on that car unless you blacked out many other things.
I'm usually not a fan of center door moldings/trim, but I think the Buick needs them to make it look right since the door is so flat. I removed the plastic strips on my Sebring and it looked HOT....not too sure on the Buick. It may just take time to get used to.