I am a pretty big "knife person" and I have to say that the only reasons I can think of to carry multiple knives is if you want one cheap one for others to use or is you also have a multi tool on you. The whole concept of a self defense blade just doesn't make sense to me unless you are an on duty cop or active military. For anything else I think one properly maintained blade should be more than sufficient. For the most part I think MNS (mall ninja syndrome) gets the best of a lot of people.
For 99.99 percent of people one knife is plenty. Do a little research on blade steels and lock types and blade grinds and start looking for something you like. For me ergonomics is also a big point but also consider the comfort of the knife in your pocket (a 6 inch beast that weighs 12 oz might look cool but probably wont be as enjoyable to carry)
Beyond that, as long as you remember that it is a knife (as said earlier, not a pry bar, if you want a blade that you can pry with buy a boker cop tool) is should cut what ever you want it to. The best thing you can do with a high dollar knife is cut every thing you can find. You spent the bucks on a cutter not a safe queen, so use it.
Also i highly recommend learning to sharpen your knives if you don't already. There's no point in owning a 100 plus dollar blade if you cant keep it sharp. Plus there is a certain type of pride that comes with knowing that you can properly maintain your knives.