Well, I've just returned....London was definitely big, but I have to say, I was rather unimpressed. Our trip comprised 7 days in Paris, and 3 in London. Despite having been told often about how rude Parisians are, I found the Londoners to generally be the ones to make tourists feel unwelcome. From hotel staff not seeming to understand that guests might be upset by a loud sound coming from their radiator at 3 in the morning, then 4, then 5, to everything closing early, not being able to take photos in several tourist locales (even without a flash), to rude staff at the Tube ticket stations.......my wife and I are not super interested in returning.
The Parisians were fantastic, with a few exceptions. One restaurant in the Latin Quarter fed me a salmon steak with a life worm still in the meat, then proceeded to charge full price for the meal. But overall, as long as you at least open a conversation in French, then switch to English as soon as you get stuck, it's fine. I speak fluent French, my wife only speaks English, so we did fine.
In London, we saw everything we could in the time we had....Kensington Gardens, Kensington Palace, Prince Albert's Memorial, Westminster Abbey (they wouldn't let us in), Buckingham Palace, the Tower of London, Tower Bridge, Big Ben, Parliament, the Courts of Justice, and Temple Church. Lots of stuff....and there's still much more to see. We're just not sure about going back.
However, we met some Irishmen in Paris, on our way to the Eiffel Tower. They were on the RER, celebrating after their rugby team got pasted by Argentina, and they were so boisterous and friendly, we actually missed our stop

If that's a typical example of Irishmen, then Ireland's going onto our list of places to visit.
I found in Paris that several people with my surname were guillotined during the French Revolution. Apparently some were nobility. So since the trip I've been trying to figure out where to start looking to find our ancestors in France. I'm not familiar with the French geneology sites/sources.
Banshee
P.S. The British Museum is one place I would have liked to have visited. If I go back to London, I'll go. But the day before going to London, we went to the Louvre, and my wife was "museumed-out" by the time we reached London.