I live near the Pacific and frequent the beach paths, and do get enough rust that it concerns me. On my latest build I took several preventative measures.

• Stainless steel dropouts, because once the paint gets chewed up, rust looks terrible. The contact areas are polished. This added about $50 to the build for labor, materials and silver braze.
• Weep holes are strategically placed and internal joints allow the frame to drain when hung by the front wheel.
• Framesaver.
• All metal axles, steer tube, BB, threads, etc are carefully coated in grease.
• Wet paint with a thick clear coat, which obscures the lugwork a bit, but rust looks worse.

My steel Zinn frame did not have these features and I would have retired it due to rust if I hadn't hated the handling and ride. It had only about 20,000 miles on it and spent most of its 20 years in the garage.