Citizens rave about Boulder's natural beauty, free spirit, plethora of intelligent and creative folks -- and now, the legal availability of recreational marijuana. With a population of just over 100,000, the city benefits from being small, but also just a stone's throw away from Denver's airports, sports teams and anything else a big city might need. There's also its central location: One can travel to either coast within a few hours.

AGENCIES
While the Sterling-Rice Group is Boulder's oldest agency, many attribute the growing number of shops within the city to MDC's Crispin Porter & Bogusky, which created a viral effect as ex-creative execs struck out on their own. Those include Made Movement (where former-Crispin creative Alex Bogusky is creative adviser); Victors & Spoils; and the newer Evolution Bureau office in Boulder.

Small indie shops like TDA Boulder are also launching or investing in their own brands like Sir Richard's Condoms.

MARKETERS
There are nine Fortune 500 companies near Boulder, although none are headquartered in the city. The biggest are Arrow Electronics, Dish Network and Liberty Interactive, all based in nearby Englewood. However, natural-food companies like Celestial Seasonings and Wild Oats are based in Boulder, as is Horizon Organic Milk.

STARTUPS
Boulder has been credited with the highest "entrepreneurial density" in the world (a term coined by startup incubator TechStars' co-founder, Brad Feld) based on how many startups and startup employees there are in the city divided by total population. According to author Richard Florida, who crunched some numbers in 2013, Boulder had about $86.9 million in venture-captial investment per 100,000 people, putting it right behind Silicon Valley and San Francisco.

OPPORTUNITIES
One word: marijuana. On Jan. 1, Colorado became the first state in the U.S. where one can legally buy recreational weed. Dispensaries that cropped up after medical marijuana became legal are now bracing for more business, mostly from tourists who might be more likely to come for ski season. That means opportunities for branding and digital shops in Boulder as dispensaries and tours look to revamp websites and identities. Denver-based Medicine Man, for example, hired local shop Philosophy for marketing efforts that include PR, e-commerce and support for a retail store. Andy Williams, president-CEO, said he plans to spend around $100,000 on marketing this year.

Pro-weed sushi chain Hapa recently introduced a pot-and-sushi pairing menu and in-restaurant displays developed by TDA Boulder. "Recreational-marijuana legalization in Colorado creates an opportunity for bold, edgy brands like Hapa to build buzz, if you'll pardon the expression," said Paul Raab, senior VP-partner at Boulder PR agency Linhart.

CULTURE
There are a number of hip, internationally recognized restaurants (Bobby Stuckey's Frasca Food and Wine set the scene) that cement the city's status as heaven for foodies who like to work out in the mornings so they can fill their bellies in the evenings.

CHALLENGES
Boulder isn't for everyone. In fact, it seems to be perfect for a very specific type of person: a natural-foods creative junkie who loves do-good technology and also happens to have a lot of money. Rents are high; so are home prices; office-lease rates are also increasing.

And because protected land surrounds the city, it can't get bigger, which means newer companies often are forced to move out.

The high cost of living and relatively fewer opportunities can make it tough to lure talent. Dave Schiff, chief creative officer at Made Movement, said he often finds that people from big cities view Boulder as a "tour of duty" they must endure to build their books or gain experience.