Thank you all for your help with the travelcard question. I think I will probably go with the 7 day Travelcard just for the convenience as Adam suggested and then purchase the one day Family Travelcards for the other few days we will be there. I think Kew Gardens is the only place we will be visiting outside of zones 1 and 2 so I will just get an extended zone travelcard for that day. Having been to London several times previously, I am familiar with the tube zones and all. I have also checked out the www.tfl.gov.uk website and printed a current tube map.
Now I have a question regarding Britrail Passes. We will be in London for twelve days and then we head to Edinburgh for four days. While in London we will be taking several day trips out by train to Bath, Windsor, Oxford, etc. and we will also be relying on train travel to get from London to Edinburgh and back. It seems as though it is a lot less expensive to get the Britrail Flexi Pass ( 8 days in two months for $579/1st Class, $385/2nd Class per adult and the 13 year old kids travel free ) as opposed to booking point to point tickets. Am I correct on that? Also, is it worth the extra amount to go with the 1st Class ticket? I think the last time I used Britrail Passes, some of the trains did not even have a 1st Class section.
PS womey - My son graduated from Apex High School. We lived in Cary!