I like the spyderdrop opening method, which doesn't work with all Spydercos, depending on the weight of the handle. Knives such as the FRN Delica, Dragonfly, Lil' Temperance, Dodo, don't open easily (if at all) using the Spyderdrop technique, so I carry them tip up. Heavier handled knives, such as the Police Model, Enduras, Goddard, etc., open very well with the Spyderdrop, so I carry them tip down. Several models don't really give you an option since they only have one, or maybe two, clip placement options. If you carry a Police model, you're going to carry it tip down if you use the clip.
There are times when I don't use the clip to carry the knife, such as when I'm wearing a leather jacket. I often have the knife simply sitting in the jacket pocket where my hand is. I can open it instantly that way.
It's nice that I have the option of carrying them either clipped to my pocket or down in the pocket, depending on the circumstances.
When I do use the clip, I always carry them in my front pocket to keep the clip from catching on things, and to make accessibility to them as fast as possible.