Hop on hop off tours vs guided tours

Both Original Sightseeing and Big Bus are similar but have different routes; you can check on their websites. And I believe you can also get discounts if you book online. Most tickets are good for 24 hours so you can go back and visit places if you didn't have time the first day.

Since the buses are doubledeckers, the senior citizen can sit on the lower deck which might be better for all if the weather isn't great. And even if it is sunny and warm, the buses swoop around London pretty fast so it can get chilly on the upper deck; jacket and sweater recommended.

Those two hop-on-hop-offs are also Rick's recommendation; he does not really recommend other bus tour companies (just other walking and bicycle tour options). It's nice to have the option to get off at any sight that interests you and restart the ride at your convenience.

We took a hop on hop off bus tour last year and enjoyed it. I can't recall which one it was - as noted in the earlier responses, there are two main ones. They both have little stands selling tickets in multiple locations. We have two young kids (ages 5 and 7 at the time) and it was a nice activity for the day of arrival when they were tired. The bus tour will give you a sense for where the top sites are located to help with siteseeing later days and will let you at least see and learn something about some of the sites you won't have time to visit. One point to keep in mind - some buses have live guides and some use recordings, so check to make sure you have a live guide.

Have fun.

We are big fans of the on/off buses when we first arrive in a city. Since most tickets are 24 hrs from the time you start, we tend to start mid afternoon and ride a complete circle just for a good orientation and to get a feel for the sites we would be most interested in visit. On the second loop we do get on and off as time permits. That evening we assess what we had seen and what to see. We will use the bus again the next day and plan to get off at the site which will take the most time to see about the time the ticket expires. We have taken both buses in London since they go to different places and routes.

Tour vs. Hopping
We almost always do a hop-on, hop-off when we get to a city we have never visited before. It's a great way to get the lay of the land, familiarize yourself with the structure of the central city, and get an idea of distances between the sights. If you see something you like, you can hop off, spend some time, and then hop back on to continue your journey. Most of these companies have a map of exactly where they go and where you can get on and off. Decide what you want to definitely get off and see the first day, and then on the second day you'll know where you should return. I think it's a good use of your time on your first day in London.

Thanks for all the tips. How's the frequency of the buses when you get off a stop - is it really just 5 to 10 mins wait for the next one?

Depends on what stop you are waiting at -- and traffic.

We have been very happy with Gray Line Tours. Sometimes we booked them while still at home; other times we have booked them after arriving in London. Gray Line Tours can be found at Gray Line Tours.com. They sub contract out their London tours to Evan Evans. We have used them to go to the Cotswold's, Windsor Castle, day tour of London, Bath, York, Stonehenge etc. Enjoy your trip. We also used the hop on, hop-off buses. We felt we learned a lot more by using a particular tour company though.