I've done a lot of work in Park Slope and I almost always drive, and I always find parking.
My secret is a Mini Cooper! I am also happy to walk and often park in Prospect Heights where parking is much easier.
There is also an application for smart phones that allows you to keep track of where you park. I always make a mental note as well.
I would definitely get rid of one of the cars, though. Parking in New York City is a nuisance you don't need more of in your life.
Licensed Real Estate Salesperson
New York, NY