Back from London.
If you go traffic is insane. Do not bother with a Hop on-Hop off. The traffic is so bad you can't get anywhere- literally impossible to do more than a couple of things a day and only if they are right net to each other. We ended up getting off and walking/taking the tube. We beat the bus we were on. They also offer a river cruise tour as an option. the wait to get the ticket was almost an hour and then there was a wait to get on the thing. (We took the city river bus). Same with the London Pass (which included the Hop on-hop off). They promised fast track but a couple of the places arbitrarily decided not to honor that. If you do decide to get one don't get it thru the Visit Britain site- they don't tell you but you don't get access to the app or some other things the London Pass site says.
Westminster Abbey Evensong has been discovered. People queue starting at 3 for the 5 oclock service. The tours are like cattle calls altho we had an excellent guide- Jane. They have opened a special tour accessed by the Poets' Corner that lets you go up into the gallery and look down on stuff- limited access- you can see all sorts of stuff below and they have original wax effigies of QEI, a few other monarchs, one of the original Magna Carta (WOW!!) that you can peruse at your leisure. Only 5 Pds.
We went to Southwark Cathedral Evensong on the south bank. BEAUTIFUL choir, we got to sit in the quire. Can't say enough.
Took Jack the ripper tour- walking and bus. The description says it gives general London tour as well as the walking tour. Some people whined but I thought it was a great way to see a lot of things. Traffic was so bad we got a chance to really look at stuff rather than fly by. Saw many of the things that I hadn't seen before on previous hop on hop off tour.
There is ugly modern construction everywhere and there is no way to take pics of anything that is considered a landmark without getting them and hundreds of cranes in the background. Almost every famous building has scaffolding on a piece of it. Parliament/Big Ben, Westminster, Buckingham Palace to name a few. .
The roads are being dug up everywhere. Cabs can't get you places- we actually had one tell us there was no way he could get us a place without taking 1.5 hours and recommended the Tube. Every surface road is congested to the point that many of the tours can't keep a schedule.
River bus is the best option to go up and down the river. The Tube is good but then you don't see the city.
The person who picked out hotel picked one on the South Bank. If you book there watch out. Not many public transport places. We walked everywhere because getting to the nearest Tube was almost as far. That is OK but you can't get back tot he Hotel easily- either a convoluted Tube ride or cab that costs a mint d/t sitting in traffic.