My novel was set in a city I know well and lived in for many years, but the city was just too big for the story. I wanted a smaller urban setting. So there is another city a few hours away from this one that I've driven through many times and probably have been to for various things, but all that was a long time ago. I plan on going out there soon. How much time would you spend in the city you are setting your novel in if you had the option? What sort of things would you make sure to see or look for to really capture the essence of this place? I'm thinking of spending a weekend, maybe a week just sort of taking this place in, walking around and talking to people. Maybe this is a multi-trip process. Maybe I should move there. How far would you go to get your setting just right?
In your situation I would make up a city name and not get distracted with accuracy. But I know that isn't what you asked. I set one novel in a place I've never been (Loch Ness). Half an hour on Google streetview was all I needed. One of my beta readers had stayed there for three weeks, and when I asked him about the setting he was surprised I'd never been there. I included more setting description than I usually do, since elements of the setting were relevant to the plot, but all I needed was a still image from Google to get it right.
I would spend as much time as possible in the area. It's not always feasible, though. My city of choice I've been to a handful of times and love it, but I live several states away now so I can't visit it anymore. The internet comes in handy because of that.
My personal choice is that if the exact location is not necessary for the plot (and I'm guessing yours isn't or you wouldn't be changing it) I say go with a fictional name and town. For example, one of my towns I always use is Grand Prairie, Kansas. I could easily use a city in Kansas I've actually lived in, but I think keeping it fictional has always worked best so you don't have to panic over accuracy and constant research (what is the name of the high school there? Is there a Starbucks in town? What's the main street in town?). I can make it up as needed.
I concur on just making up a fictitious City/Town/Community. Or you can really have some fun, and mess with a bit of geography. Search for a small town (preferably not in your own state), and then seed it into your stories state. Take the now empty town of Amboy out in the middle of the desert in SoCal (Had a Pop. 20, gas station, and a school). Now put it somewhere like an hour west of Pittsburgh, PA. It can be your own little Easter Egg, and your readers might find it amusing.
A lot depends on whether or not the town is almost like an additional character in the story. In that situation, then yes, spend as much time as possible there. If the story could take place pretty much anywhere, then it isn't as necessary. I prefer real towns in novels to fictional ones (but I do want them well-researched and "real.") Fictional towns bore me and tend to take me out of the story, because there are so few authors that do ficitonal towns very well.
This is why I set all my stories in the general Pacific Northwest. Either I'll say Portland, Seattle, Olympia, Bend, etc. Or I'll just make an amalgam of all those cities into one. I love the idea of setting stories in France and Belgium, but I haven't been there yet, I'd like to spend a few months in each if I could. Architecture and the nature of the countrysides and cities. I'd make sure I got things correct like the colors of the skies at dawns and dusks, and feel of the weather.
I agree with @Shenanigator - there are books in which the town is very much a character in the story, and books in which the town is just a place for the story to be set because it has to be set somewhere. If the latter, I don't think you need much real-world knowledge, but if the former, I think the more time you can spend there, the better.
Someone said google street view. I prefer google earth. It is a better tool if terrain is an important factor. You can also measure distances easily with it. I have ideas in the works that involve Prague and Belfast and do not have the budget to visit those.
It's more about getting a feel for the local flavor than how the city of its buildings look. I recently went to a diner/bar in this city and it was exactly what I was looking for. I'm not going to go overboard with the setting, I just want what I do put down to ring true for those who know. Thanks for all your help, everyone.