When I was in my twenties and early thirties, I gravitated towards large urban centers, where things were happening and I felt connected to the city's pulse. Now that I'm older, I find myself looking for a mix of both; desiring access to events and activities while maintaining a sense of community and quiet living. This isn't an easy mix to find, so now when I seek the next place to live, I look at size of city compared to its offerings.
If you need a little mix of both, then you should look at what size of city or town you prefer. Are you into the urban scene or do you prefer the quiet, easy-going streets of a small town? Does the city you're considering have small neighborhoods that can offer a small-town feel? Can you live in a small town that's close to a larger city, still giving you access to the arts and cultural scene?
To find out which city or town is best for you check out an article on city comparison tools. Also read the article, How to Compare Cities for information on everything you need to know about finding the right place for you.