I remember once Dave talked about how he'd read a scholarly article that posited that the ideal population size for a city is either 100 000 or 200 000.  I forget which.  He'd remember.  But anyway, based on certain criteria, that's what a select group of people came up with.
I think a city should be big enough, and well-planned out enough, to have good public transit and a wide array of cultural and recreational activities, but not so big that it takes you an hour and a half to drive or commute to work in the morning, or so that you cannot enjoy the array of cultural and recreational activities.  Whenever we go to the Lower Mainland, I'm so glad I don't live in such a traffic-y place.  My uncle's commute to work in the morning can take anywhere from 30 to 120 mins, depending on traffic, even if he leaves at the same time.  That's bonkers.
I like busy beaches.  You get a certain sense of community, even though you may be packed onto Third Beach in Stanley Park with hundreds of strangers.  It's kind of fun having all of those people around and being able to people watch.