Hi Kathy
I have to disagree with some of the advice given to you here. I've recently been "rediscovering" London after living in Spain for many years and am writing a blog about my days out in London. I've used the London Pass several times this year and its great value for money. You also get to jump line which saves quite a bit of time at the big sightseeing places.
If all you want to do is see the outside of buildings then, sure, sit on a bus for several hours but you won't get to experience London properly... and if you get stuck in traffic queues or are on diversion you will get very frustrated!
You have a couple of weeks til you arrive so I strongly recommend using the London Pass site (
www.londonpass.com) to plan your itinerary so you don't waste time on unnecessary travel and you will find you can fit loads into 2 days. Also, if you plan in advance you can make sure you DEFINITELY save money... with a 2 day pass it's hard not to make a few bucks profit!!! London Pass also gives you discounts and offers at various restaurants and bars and also on theatre tickets so check that out too!
There is definitely more to London than sitting on a bus for two days!!! And, believe me when I say that London also has a lot more to offer than just museums... do your research and you'll see what I mean!
I really hope you enjoy your brief time in London - it is a great city so don't waste your time just sitting on a bus with a map looking at buildings... please
Best Wishes
Sparkly Songbird x