Brussels or London Day Trip from Paris

EuroStar high speed train makes a day trip possible, although it's a long day. Rick's London book describes a day trip to Paris from London.

Sure, if you don't mind spending a looong day touring. Check www.eurostar.com for tickets to/from London....and http://www.sncf.fr/indexe.htm for Thalys tickets to/from Brussels. For Brussels, you can leave Paris at 6:30 and get into Brussels at 7:45 at the earliest, then leave at 8:45 pm and get in to Paris Nord around 10 pm. By booking early, you can get fares as low as 54 Euro pp return (non refundable, non changeable Smilys tickets.) For London, you can leave as early as 7:15 and get in at 8:55 am (you gain an hour in the time change), then leave as late as 7:45 pm and get in at about 11:20 pm (losing that hour back again. That's be more expensive, at about 120 Euro pp.

Are there tour buses to pick up at Waterloo in London?

There are tour hop-on-off tour buses at Waterloo, buy you are better off walking to the London Eye which is a block away. At the Eye explore the attractions nearby, then cross the bridge to Big Ben/houses of Parliament, and then walk to Westminster Abbey. From the Abbey you can catch the tour bus to the other attractions, or take the Underground.

London, without a doubt. It will be a long day but take the early train in and the latest train back. London has so much to see that a day will just give you a small taste. Take a hop on bus tour. You can stop to see the things you're really interested in. One also includes your choice of walking tours. You'll get to see Westminster, Big Ben, Parliament, Buckingham Palace, Trafalgar,Tower Bridge and the Tower of London. Much more to see than in Brussels. I did it the other way aroung (London to Paris)and stayed over one night.I know lots of people will disagree, but I prefer London to Paris. Either way, have a great trip.