Ocean salt if pretty insignificant when they are throwing down salt in the winter on the east coast. IF that is where you are worry about that instead. Just my .02 cents
I'm in the Coast Guard at a small boat station in Jersey. Our station and parking lot are less than a mile from the beach itself. I wash my car at least once a week. You'd be surprised what the salt air will do to rotors and anything else that isn't very salt tolerant. I don't know how far inland you'd have to go to keep it not a factor, but I'd say if you live close to the beach, wash the car at least once a week and keep a good coat of wax and polish on the paint and anything chrome or even stainless. My SS exhaust tips started to pit from being down here, I polished the crap out of them with mother's and I need to keep a fresh coat on there once a week. The undercariage and engine compartment are usually protected.
I live three miles from the beach and have an Explorer that has spent it's entire life outside and it has no rust. It only gets washed once a month and waxed every three months at the most.
But a friend of mine lives on the beach in Hermosa. He parks in the underground parking lot that is open to the ocean on three sides. His 2000GT is washed maybe once a month and has NEVER been waxed. Paint still looks good but the bare aluminum intake on the engine is starting to corrode. Haven't noticed any other rust anywhere else. If he had taken even the slighest precaution against salt air he would'nt even have that much damage. There is a kid in the same building that has his dirt bike parked in the next stall over. The bike is six years old and look like brand new. He washes it all the time and wipes the engine down with WD-40 or some kind of detailer. Not a speck of rust or corrosion.