If you don't have a 7 day travelcard for zones 1 2, either paper or on an oyster card, any day you o

I have seen recommendations last minute travel websites in canada for do it yourself bus tours of London using the 11, 9, 15 and 136 bus routes. I also seem to recall that on a couple of the routes, the old style buses are used. I think the 15 is one of the "Heritage" routes, but not sure of the other. Does anyone have a more specific recommendation about the various routes? Where would you begin if you were going to do your own tour? Where, generally, do the various routes go? Or is there perhaps an old thread discussing this that I haven't found? We are staying near Westminster Abbey, and the 11 goes right by. It looks like it will take us up Whitehall, through Trafalgar Square, and then to St. Paul's and that we could then switch to the 15 and go to the Tower. Any recommendations for other specific routes?
If you don't have a 7 day travelcard for zones 1 2, either paper or on an oyster card, any day you only use the buses and use your oyster card PAYG, the one day bus fare will cap at I believe 4 somewhat cheaper than a one day travelcard (there last minute travel websites in canada are no paper one day bus tickets available any longer).
Terrific link mscleo! Thanks so much. That entire website seems interesting, last minute travel websites in canada especially some of the walks. It also contained a link to some audio tours, including podcasts that look interesting. And PatrickLondon, thanks for the link to the pdf guide. last minute travel websites in canada It has good info. Appreciate it.