Anyway, here's my more relevant post.
Spyderco loves trying out new steels. They love trying out new locks, and have many different lock types under their belt. I can think of liner locks, back locks, frame locks, compression, caged ball, power lock, slip joint...I'm sure there are others. Combined with the steel choices, it makes for an impressive variety that allows one to find THE perfect steel and style they're looking for.
Sprint runs. Not only does Spyderco experiment with different steels, they also make limited runs of their most popular knives in many, many versions with different premium steels and handles.
Focus on cutting ability and ergonomics. By far, Spyderco is the company most concerned with making sure all their knives cut efficiently and are comfortable in the hand in a variety of grips. As some people think, this comes at the cost of focusing less on aesthetics and more on how the knife works and feels.
Full flat grinds. Enough said.
From my personal experience, a Spyderco will convince someone to make the jump into the upper level production knives better than a ZT or Benchmade. Why? Because they hit the sweet spot of performance in the $50-120 range. They start hitting the more robust steels as designs at a lower price point than the competitors, minus say the S30v versions of the Kershaw Blur and Skyline. They also appeal to someone who is unsure about spending the money, but can relate to a hard working knife simply because if feels good and looks like it is meant for work. Again, personal experience with convincing people to buy Spyderco.