Another thought, the comments about "tacti-cool" are worth considering; many "tactical" knives make excellent EDCs but some are simply designed to give mall ninjas a feeling of satisfaction when they flip it open.
Personally I think that assisted opening, etc. is a gimmick and one that I can do without. If I'm in a situation where the slight increase in speed of opening of an assisted knife makes a meaningful difference over how fast I can deploy a good modern folder like a Benchmade or Emerson with the thumb studs alone, I've apparently made some poor choices in my life. Also keep in mind how some people are very nervous and fearful... if you have an overly tactical looking folder in your pocket, simply pulling it to open a box or envelope or something can get you some sideways looks and maybe a comment like "who does this guy think he is, Rambo or something?" (also, unassisted opening helps here too, the loud "snick" of an assisted folder flipping open can result in OMG SWITCHBLADE and a visit from the local rentacop or a talking-to by HR, whereas if you're not in a hurry, you can open an unassisted knife slowly and quietly...) This is why I'm partial to non-black, non-camo, typical drop point non-serrated blade shape etc. It's sad that we have to take this into account, but we do, and I don't want to unnecessarily put people off just because I carry a pocketknife that is large enough to not be a toy.
Also research your local laws as to what you are and aren't allowed to carry in your area. Believe it or not, knives are as tightly regulated as firearms although it doesn't seem to be as widely publicized that that is the case. Around here (VA) I can't legally carry a blade longer than 3" in a school, for example (and it must be a folding blade; apparently fixed blade knives are completely prohibited) and my CCW gives me no exemption whatsoever from any knife laws; in VA a CCW is strictly for handguns only.
In most cases, a knife longer than 2.5" is prohibited in Federal buildings - including post offices - although some places may prohibit knives altogether. Just how silly this is is evident when you realize that most SAKs have a primary blade longer than that, as do most traditional trappers etc. But that is the law... I do have one "short" knife for just such an occasion (Kershaw Scallion) but it is assisted... only thing I could find. C'est la vie, I'm sure if I ever get confronted about it I'll have to give it up, but it's one of those things, like having a flashlight on you, or a lug wrench and jumper cables in the trunk of your car, without which I feel naked leaving the house...