I like to visit big cities, have lived in a couple (Chicago, Beijing). My idea of visiting a city does not include a daily commute from a suburb, seeing the city only during commuter hours. I want to be in the middle of things from when I get up (which might be dawn) until I am ready to go to bed (which might be dawn).
That means driving in or flying in, getting a hotel in the middle of where I want to be in the evening, with mass transit or pedestrian access to where I want to be during the day, while transit is running. You don't drive around in a big city, RV or car, because there is usually no place to park where you want to go. If you have to drive in, you park the car for your stay, the get around the way the citizens do. The people who actually live in the city don't drive either, most of those private cars are folks from the suburbs coming in for the day.
It is the way I've handled big cities and small cities: London, Paris, Hong Kong, Singapore, Madrid, Barcelona, Lisbon, San Antonio, Houston, Dallas, San Diego, DC, Chicago, Rome, Kunming, Nashville, Detroit. Well OK, in Nashville, Dallas, Houston, Detroit I do drive, because mass transit doesn't work well there, but they are not really cities either, more like overgrown suburbs lacking a geographic focus.
When I was in Chicago again last month, stayed on North Michigan within walking distance of the Blues Festival and the night life of Navy Pier and the near north side. I have a trip scheduled for New York, about a week at a hotel just off of Times Square. I am going to fly in. I have to see New York because it is simply a shame that I've been to Lisbon and Rome three times each, London at least six times for extended stays, and have not yet visited the only equivalent city in the U.S.
I've done some of the bus tours, it is sort of a way to see "yes, looks like a city there" but not really experience it. It is also a way to get started, but even then a "hop on, hop off" is usually more useful than seen the city only through the window of a motorcoach. The bus tour may not be bad, if you really don't like cities, or are afraid of them, and want to say you've been there, seen the, but don't want to experience anything city.