Sight seeing trips around london?

Question

Who does it the best, without jamming passengers into a tight mini bus. Day or evening trips please

Answer 1

Jemima, why don't you take one of "City Sightseeing's" Open-Top Bus tours?
You know, the big double-deckers (very London!)- you don't feel the least bit like a sardine on those.

From a tourist website:
Enjoy your trip around London on the top deck of one of our double decker buses. You almost get a birds eye view of London's famous attractions.
We stop at over 80 places, so you can hop-off, explore, have lunch, then hop-on the next bus along.
Your ticket is valid for 24 hours from the time that you first hop-on.
Our buses run from 10am until 6pm 7 days a week, 365 days a year.
Free River Cruise included in the tour price. (From 17 pound).

http://www.virtual-london.com/sightseeing/sightseeing-tours/bus-and-coach-sightseeing-tours/london-open-top-buses/open-top-bus-tour-of-london.html