Mind the leash
There are almost as many dogs in Boulder as people. Be mindful that not all trails allow dogs, and even those that do may require a leash. Some trails allow off-leash dogs but they must have a voice-and-sight tag to be off-leash. Within the city limits, all dogs are required to be on a leash and dogs, even on a leash, are not allowed on the Pearl Street pedestrian mall (although I've seen a few toy-sized ones being carried around).
Dog regs for open space: http://bouldercolorado.gov/index.php?option=com_content&task=view&id=3051&Itemid=1041
Boulder has one of the highest per capita residents with college degrees in the U.S. The library is a reflection of this. Built in 1999, this library is a work of art. Top of the line internet, and a huge selection of books, magazines and newspapers from the world. The fact that it has a view of the creek on one side, and the mountains on the other makes this a very popular place for the locals.
Everybody is so fit!
This town is into fitness like none I've ever seen. EVERYONE was in great shape. People are constantly jogging, biking, hiking and walking. I thought Floridians were fit, but Boulder takes it to a whole new level. Plus, there are a a lot less boob jobs here.
When radio host Peter Sagal visited Boulder the second time, he joked that he needed to replace his vest, made from "the wild polyesters that roam the flatirons."
Vests, especially fleece vests, are a frequent part of the local costume. At times it seems like something of an affectation - certainly Boulderites are not above such things. And a fleece vest is at once high-tech and hippie-retro (very Boulder). However, in a city where daytime and evening temperatures fluctuate widely, and physical activity is highly valued, the vest also has a certain practical value. Like the expensive sunglasses that protect your eyes from excessive UV at high altitudes, vests might be a practical affectation.
Leave the Pro-Bush bumper stickers at home
Boulder is a very liberal and Democratic town. Anti-war protests are common on the corner of Canyon and Broadway. If you don't want to get into a confrontation, keep any conservative views to yourself.
Be prepared for all types of...
Be prepared for all types of people on the Pearl Street Mall. Beggars are a-plenty --- many many of them in their late teens! There are Buskers which make the Pearl Street scene a fun place to be - watch and listen!
Boulder is a very laid-back...
Boulder is a very laid-back and friendly place: Never honk your horn casually in traffic, always smile and say hello when passing someone on a hiking trail (even if you don't know them), and never wear a tie to dinner.
Typical Rocky Mountain...
Typical Rocky Mountain lifestyles. Meaning pretty homogenized America. It is still an ever shrinking bastion of liberal thought though. One of the last remaining 'free' places of Colorado. The state in general is getting to be very right-wing republican and not in a good way (as if there could be one). One of Boulder's chief concerns is growth or better yet the need for a lack of it. The environment can't handle it and this shows in the attitudes of Boulderites. But, as growth is, it can't be stopped-only slowed. It's a lose/lose situation and Colorado and Boulder will eventually pay for it.
More than just snowboarding
Boulder has one of the highest percentage of acedemics anywhere. Boulder University is one of the largest in the Western United States. The rest are going to have to go a long way to upstage CU.
A 10k race held every Memorial Day weekend. The race draws large crowds from the local area and Denver.