I have been reading your writtings and here are my thoughts about the "street lens".
I have 1*20D and 1*350 D.
To begin with I should have bought 2*20D to work with two iddentical cams, what is easier on the scene ...
Lenses: 16-35 f/2.8 my 1.st, then a 24-70 f/2.8 and at last the 70-200 IS L USM f/2.8
When I had only the 2 first lenses I was using only the 20D.The 350D was for my wife before she gave up and turned to the old Sony xyz.
Then I was changing lenses all the time, or sometimes.
When she gave up the 350D I decided I would carry 2 cams: the 20D with the 16-35 and the 350D with the 70-200.
This avoids me the annoyance of the dust on sensors when changing lenses.
So, the 24-70 is parked at home.
I was, before having all these lenses, a lover of whide angles and I still am. But each lens has it's own use.
I like to 70-200 for it's versatility for rather long distance shots like portraits.
But I do like the 16-35 also very much because it captures the mood of the place very well.
Then, my street lens is ... no, are: 16-35 and 70-200.
I am going to India next month. I'll take both lenses, a flash, CPF and ND. No tripod.
I have to think about my backs. With two cams and these lenses I can (almost) cover any situation. May be I would like something whider for some times... but one can't have everything in life.
I read somewhere here in the net - from a professional - that the 24-105 was not a good lens. It sucks he said. He looked like an expert because he had some very nice tuttorials on line. (If I looked I could find him but is not the point here).
But one thing I am sure (and I am not sure of many things in life):
a lens with large apperture is a plus.
I post here two pictures. The 1.st with the 16-35. This picture would not (?) be possible with any other lens.
"The place is very difficult... It is a cave, low light, 3200 ISO f/2.8 slow speed in the limit or over the handheld ...
Only with a lens like the 16-35 f/2.8 (or one like the new one from Canon 24-105 f/4.0 with IS ? ) this is possible.
I had sustained my breath, legs apart, arms close to the body and took several shots.
In the cave men collect the nests from swallows, climbing throught bamboo scarfolds endangering their lives ...
The nests are sold in Japan at huge prices cooked as soop.
I really wanted to taste but it was not available ...
The smell in the cave is kind of disgusting, interesting, strange and agressive: the mixture of the excrements of the birds from many many years ... amoniac smell !
There are "villages" of cocroaches also. On the walls. Interesting.
Excrements may fall on your head !"
The light on his head should be on. I couldn't remember at the time...
The other with the 70-200 in a complete different situation.
Hope I made myself understand. Thank you for reading.