With proper care, stainless steel sinks can last a lifetime. While not as scratch-resistant as granite, brushed-and-polished finishes on stainless steel can easily remove scratches and scuff marks that appear over time. They're also simple to keep clean - being resistant against food grease stains as well as mildew growth.
Avoid cleaners that contain chlorides (such as bleach, drain cleaners and even toothpaste), and utilize a non-metal scouring pad to scrub the sink's surface. Metal on metal contact can result in permanent scratches; to minimize their risk avoid leaving pots or pans in your sink for extended periods of time.
Consider also the grade of stainless steel used to construct your sink, as higher grades tend to be more durable and corrosion resistant. Look for one with higher levels of chromium relative to nickel for improved resistance against tarnishing; an ideal grade would be 18% chromium stainless steel although other grades exist as well.
A stainless steel sink's gauge number indicates its thickness. As its gauge number decreases, so will its thickness. A thinner gauge sink offers greater durability while offering sound-absorption properties and increasing collective strength. If purchasing new sinks, aim for 16 gauge or lower as this will save money over a thicker option.