Over the past 10 years I have taken space in 3 distinctly different shared office spaces. Interestingly enough, while the "coolness" factor might have increased with each move, the collaborative/entrepreneurial culture has gone in the opposite direction.
Space 1 - A mix of independent movie makers, software developers and 3D animators. Space had a lot of windows, but had old couches, carpets and felt like a garage sale could break out any minute. That said, the culture was extremely collaborative and had an almost tangible entreprenerial passion in the air.
Space 2- A mix of an advertising agency, law firm, temp-agency and a technology company (me). The space was a very "cool" SOHO NY loft type space with an Orange Crush theme. While clients were impressed when they visited me, the amount of interaction/collaboration between the companies sharing the space was minimal aside from some legal guidance.
Space 3- A mix of a world class architectural firm and a technology company (me). The space is worthy of design awards and yet there seems is almost no collaboration/passion...at least from an entrepreneurial standpoint.
While I understand there are differences between a coworking space and a traditional shared space, the lesson I have learned is that it's the culture and not the "coolness" of the office that makes it feel right or not.
In addition to my company's main goal of facilitating the interaction between individuals/companies burdened with unused (spare) office space and small businesses/entrepreneurs looking to find the "perfect office" space at the right price, we are also committed to helping promote coworking space.
To keep abreast of the coworking trend, I spend a lot of time reading the various threads on the Coworking Google Group (great information there). The theme I have noticed is that the coworking spaces that have the strongest culture tend to be the most outspoken on the thread, the most successful and perhaps the best models to follow.
Depending on the layout of your space and how much privacy you can offer, perhaps its a good idea to clearly define the culture you are trying to create and the types of companies that would fit into this culture. Doing so might make for a much more productive/collaborative environment, which in turn will lead to a more successful coworking environment than simply having the "coolest" office space in town.