I have led and assisted a range of trips, including visits to Washington DC and San Francisco, various trips to Berlin and numerous visits to the Western Front around Ypres and the Somme - though have been a relative late-comer to TCBC, having being introduced by a colleague.
What immediately impressed me was the level of organisation and quality of contact - as a busy Head of Department it is great to know that the planning and booking is being taken care of, with regular updates and suggestions for visits, restaurants etc - their on the ground knowledge of the city is amazing! We were also very impressed by the quality of the guide that was provided, he really made a difference to our trip satisfaction!
Our pupils really benefited from visiting Washington - those studying A Level Politics were able to walk through the corridors of the Supreme Court and Congress, and our Historians were able to stand on the steps of the Lincoln Memorial with the view of the reflecting pool in front of them - which they found really engaging and encouraged them to develop their knowledge and interest, which can only be positive.
My advice to anyone running a trip for the first time would be to not go overboard on the itinerary. A few well-chosen visits or activities per day is far better than racing around trying to fit everything in, with little time to actually experience what you are there to see.