I chatted with a bar manager once who was fretting about the parking availability. I was pretty astounded that this was a concern as I'd bet 70%+ of his patrons walked/used transit/took a cab to and from the place. And, you know, if you're running a bar you should be pretty happy about that due to host liability issues. But it's the drivers who complain.
But more generally, how many spots and where? Are one dozen extra spots nearby going to transform your business in a neighborhood with other retail uses? 20? 50? Where are they going to go?
Parking takes up a lot of space. Unless you want suburban shopping mall levels of parking, it's hard to imagine that a few spots here and there are really going to make a difference to your business.