Most major cities can be appreciated given the right circumstances. Managing your expectations is also important.

My overrated cities:

• L.A. - too spread out, nothing really special
• Wash DC - almost doesn't count because it doesn't have a great reputation either. It's expensive and I find people there smug.
• Berlin - it's nice, but there is little to visit/do. NOTHING is open on Sundays.
• Frankfurt - I had read so much about how int'l, diverse and modern it was before going there. It might have been modern in the 80's or early 90's, for such a diverse city nobody speaks English (I got by with big efforts and the very, very little German I speak/understand). BORING.
• Zürich: good food, but incredibly boring otherwise.

PARIS: I lived there for 6 months and loved it. I saw lots of tourists with infants and/or toddlers and couldn't help thinking they were all idiots. Paris is NOT a place to visit with young kids, much like Disneyland is not a place for a bachelor party. I truly believe that tourists who find people in Paris rude only do so because of preconceptions. They go there thinking "the French are rude and they hate Americans" and that's what they experience. Go there with a different mindset and you'll see what I'm talking about...

Vegas is great for what it is. (Again, manage your expectations!)

I LOVE NYC! The fact that NYers are rude, or that the city is polluted... these are just chichés, IMO. There's a lot to do, great food, excellent shopping, etc. More importantly, it has a unique atmosphere, a feeling you only get when you're in NYC.