Not every street has to have a specific name as long as you create a believable flavor for the city. For example, the world Harry Dresden inhabits "feels" like Chicago. Butcher seems to have picked just a few key ingredients of Chicago life: bars, extremely cold winters, towering buildings downtown, and has expanded on those aspects of Dresden's Chicago (that's the key, btw. It's Dresden's Chicago, not Chicago, Illinois).
This is, I think, essential and needs repeating and emphasizing.
Pick a city you think is interesting, any city. Do some research, yes, but what your initial research should be aimed toward is the creation of a list. List a few specific landmarks, write bullet-point words about the feel of the city. If it's a large city, add a few neighborhoods and specific one- or two-word descriptions of each.
Say you wanted to use Washington DC as an example. Your list might look like this:
LANDMARKS
- Washington Monument & "The Mall"
- Capitol building
- Smithsonian Museums
- Metro railway
- cherry trees, springtime Cherry Blossom festival
MISCELLANY
- Politics
- Business suits + extreme poverty
- Tourists
- Cocentric circular design
- Big football town
NEIGHBORHOODS
- Northwest = affluence, gentility, Jewish bakeries
- Northeast = gentrifying, arty, Union Station
- Southeast = crime, poverty, vandals, new ballpark
- Capitol Hill = Bluetooth & briefcase crowd
And that would be enough to get you started. As you wrote, you might want to look up a specific restaurant or have a map handy to pick up a street name here and there, but you wouldn't need to have a specific reference every single page or even every single chapter.