I'm soooo confused!! Right now I have plane travel and hotel booked for 12 days landing in London returning from Paris, this can be changed. Should I split the time between the 2 cities or add another destination. Thanks for any ideas you may have.
I echo the other advice. You can take day tours. Get a London Pass. Get an oyster card for the tube. Walk around. Have a good time. Both cities are interesting. We took an Evan Evans tour to Oxford/Stratford, etc.....guide and driver were great. The Marriott hotel was great.
You'll have so much to do between the two cities its crazy. As others have said day trips to places like Oxford or Cambridge are definitely things to do and you can reach them via the rail services from London. Also, look at the Stansted Express (http://www.stanstedexpress.com/), you can rent a car there and easily drive around the UK countryside. There are fewer Marriotts up that way but there are some amazing Best Westerns if you overnight up there. And no they are not like BWs here, these are actually pretty nice in some cases. :) From Stansted you can also catch day flights on Ryan Air (http://www.ryanair.com/en ) to most any place in Europe for almost nothing (day trip to Dublin is something like 30 GBP per person. As for Paris, there's an amazing list of things to do and there's plenty of places you can day trip to from there. Brussels or Cologne are pretty cheap and excellent destinations for a day if you haven't been. Of course you could easily spend all 12 days in just one of these two cities. :) Have a blast & take lots of pictures.
Check out the Insiders comments for London and Paris. Likewise, take the Eurostar between the two cities for a real thrill. You may want to spend a day in Normandy, if you are into WWII history. Don't forget Versailles and the countryside in both cities! Have fun!
Twelve days is a lot for two cities, even if they are my two favorite in the entire world. If money is not an issue, all attempts should be made to fly to Venice for 3 full days. I made my first visit there in June and it exceeded my expectations on all fronts. If Venice isn't possible, then Berlin would be my second choice.