What Makes a City Usable?

Last week I was in Portland Oregon for the Usability Professional's Association Conference. It's my second time in Portland, and I was struck again with how comfortable Portland feels. A common phrase I kept hearing on this trip while talking with people from the conference was, "Have you been to Portland before? It seems like such a nice city." So I've been thinking in the last few days about the concept of a usable city. What makes Portland seem so nice? What makes it feel "usable". Here are some ideas:

1) Manageable scale: Portland is a manageable city and has a "usable scale". Meaning, it's not too big and not too small. You can get a handle on it, but there's still lots to see. There are some nice looking larger buildings to look at, but it's not overwhelming.

2) Balance of urban and nature: Portland has a good mix of urban life (sidewalks, stores, cafes) and green spaces (parks, places to sit outdoors). I was especially struck with the idea of a small square in the middle of the downtown that had flowers and Adirondack type chairs where people sat reading.

3) Diversity of people: As you walked the streets there were people young, old, hip, square, all different colors.

4) Get to the airport in 30 minutes for $2.40: OK, I was REALLY impressed with the light rail system... I walk out of my downtown hotel. I walk one very short block with my backpack and roller luggage. I get to the corner and buy myself a ticket for the light rail (the machine for purchasing a ticket is NOT very usable, especially early in the morning by a first time user... that they can improve on). I don't have to go down an escalator or a set of stairs... so it's easy with luggage. I just get my ticket from a machine on the street. The light rail train arrives even before I've gotten my ticket. It says AIRPORT in big letters. I get on (no steps, just roll the luggage right on) and ride the train about 30 minutes to the airport. It's quiet enough that I talk on my cell phone without any problem. Best of all, when I arrive at the airport and the door opens I'm IN the airport with the ticket counter in front of me. THAT was impressive. A cab to the airport costs $40... light rail $2.40...same amount of time...

5) Cacao liquid chocolate shoppe: I have to admit that Portland seemed most wonderful and usable after we found the Cacao shop across from our hotel. It's a small place, with only room for 3 people to sit on stools looking out the window. You order a "shot" of liquid chocolate in one of 3 flavors and sip your warm thick chocolate while watching a soft mist fall outside and talk with friends. It changes your perspective on your day.

I'll visit Portland again!

So what do you think? What cities would you nominate as being usable?