Jose --- from what I can tell, there are in fact 3 categories:

(1) The look/feel designers

(2) The UX/IA people who spend most of their time in wireframe

(3) The "developers" who hook things up and get things running.

The difference between (1) and (2) is pretty huge. I've been disappointed on projects that needed strong look/feel but got mostly IA/UX. Here's more advice to readers: you're going to feel like you're "supposed" to want IA and UX. Fuck that. If you want to look cool, clearly communicate that that's what you want.

1 and 2 can be separate, but there are a lot of people whom can do both well. That's not to say that there aren't also a lot of people whom are horrible at one and great at the other. the "look/feel" designers are more of graphic artists then UX/UI people. A good team should be composed of people from each of the 3 elements you described.

No matter whom you decide to go with look at the portfolio first. I can't emphasize this enough. If you don't like what they've done before then chances are you won't like what they'll do for you. If you want a "cool flashy site" find a person that builds great "cool flashy sites". Don't go for the person that loves minimalism.

Whenever I build a UI team I look at the portfolio first. If I like what I see then I look at the credentials and where they've worked. Otherwise I pass.

Richesh, From reading your updates it sounds like you want a graphic designer and not a UI designer. If you have a structure and layout that you like and just need someone to make shiny buttons and give you a good color palette then a graphic designer is what you're looking for.

I'm looking for the "look & feel" designer. We have 3 developers on staff, we have come up with basic site layout, and color scheme but we need to make it easy on the eyes and "attractive".

You don't want UX/IA. Putting UX in this request will add several thousand dollars to the project cost and probably diminish the value of the deliverable.