When I was a full-time CFI, I would not sign off a private pilot student until they had been with me to a Class B airport and a grass strip. My logic was they'd be used to the 5500' paved nontowered airport just outside a Class B where they learned, but they should have as wide an exposure to other airports as possible. Most of my students loved doing both the grass and the Bravo.
I love going in to Class B in light airplanes ... my goal is to hit them all eventually. I've done quite a few: EWR, JFK, BWI, IAD, CLT, ATL, MCO, MEM, PHL, PIT, MCI, IAH, DAL, HOU, and DTW. Did DTW in a snowstorm, BWI in low IFR, EWR in the rain. I almost always go IFR (obviously). As mentioned, you are the PIC and safety is priority one, but it'll make ATC a lot happier if you can keep the speed up. I did several of these airports in a Bonanza and planned 160 to the marker (clean) and 140 (gear down, apch flaps) inside, usually landed with approach flaps. Did several in Cherokees and 172s though and 120 knots to short final (assuming smooth air, of course) was always enough to make the controllers happy.
If you go in to a distant B IFR file or expect the appropriate STAR and be familiar with the fixes on it. I went to IAD several times and was always assigned the JASEN arrival, which has many fixes on it and controllers who will shortcut you (such as "after DOCCS direct JASEN rejoin the arrival"). Study thoroughly the airport diagram and know where the FBO is before you land. Don't be afraid to ask for progressive taxi ... large airports can be more difficult to navigate on the ground than they appear on the diagram. Take somebody with you who is comfortable with it, be prepared to cough up some fees, but go for it. Except for DCA, which is punitively closed to all but the airlines for no good reason, you can take a single-engine airplane in to any Class B in the country. Only catches are JFK and LGA ... at JFK you need slots between 3pm and 8pm and at LGA between 6am and midnight.
EWR is a blast, the controllers are helpful (though they talk VERY fast), and you get a great view of Manhattan on the way in.
Good luck!
FL270