Depends on what city, what kind of traffic, what time of day, and what are the rules. It is not just that your motorhome is long and has a wide turning circle, it is also that it is probably 8 1/2 feet wide. On many city streets you'll sometimes have as little as 10 feet between the cars parked at the curb on each side.
Large vehicles have to go into big cities, but there are specific streets they are allowed to use, and drivers are supposed to know which streets these are. There may be times of day when they can go in, go through, or use specific streets. This tends to be mixed with parking regulations, i.e. parked cars are taken off certain streets during the hours used by sanitation trucks, delivery trucks, and street cleaners.
One might argue that there has to be room for ambulances and fire trucks to get through, but they have a privilege: when they get to a place where only one vehicle can squeeze through, everybody else has to yield.
What it amounts to, yes you can do it, but you have to know what you are doing. For each city, there is information, detail, you need to have. You can get around, but you might not be able to go everywhere you might go with a smaller car.
Real experience? I have no problem with my 30-feet 102-wide 11 1/2 tall motorhome on most of the major arteries in the Detroit area and suburbs, as I lived there my first 22 years, six years of driving those streets professionally. Mostly, that would be the spoke boulevards, the mile roads, and in some areas, the half-mile roads which are often the arteries for industrial deliveries.
I know where I can go and can't go in Lansing, Michigan, with six years living in the area and at least annual visits in the 35 years since leaving.
After four years living in Chicago, I know how to get through, a few places where I might take a motorhome, a lot of places where I absolutely cannot go, and a lot more where I might be permitted but would not want to try. I would need to refresh my knowledge, because some of the streets I would have used in the 1970s are now closed to all private traffic, and many of the daytime truck routes have changed.
I know Houston well enough to get around on major arteries outside the 610 loop, know how to get in and out of the Texas Medical Center on surface streets, know that there are a lot of residential areas I would need to stay out of. In practice, I've limited my motorhome driving to stay outside the 1960 Loop except for going through on the freeways or toll roads, and I've gotten trapped by lack of room to move as far outside the city as Katy.
I know where I can and can't go with my motorhome in San Antonio, where there are some streets officially closed to large vehicles, and others closed at times to all private vehicle traffic.
I know enough about traffic in Manhattan to know that getting around is possible, but I don't know enough of the rules to even try.
Midsize midwestern cities like St Louis, Kansas City, Indianapolis, yes you can get around, but no, I don't know the details of how to do it. Indianapolis surface traffic patterns have changed drastically since I lived there, chopped up by running the Interstates into and through the city.
Older cities like Nashville, Charlotte, Atlanta are a lot trickier because of pre-automobile street patterns, but I've managed to get to my daughter's location in Nashville, though it helps that this was in an industrial area with a concentration of truck and rail terminals. Other residential areas of Nashville, and some commercial areas, I would not take a motorhome.
