Long Focal Lenghts..... Not portrait purposes......

Hi,

I tried to wolk for the city using a tripod and 135mm lens and I discover a world where I can go inside remaining on the edge of it....
I want to say that I loved to take pictures of people making things, working, talking etc... without being so much close to them interacting in some way...
Do anybody has experience on this kind of shots?
Which is a good focal lenght to use for those purposes?
I really dont use so much to take portraits and I didn't think long focal lenght were good for me.... But... I discover a nice way of shooting I think.
Please, give me suggestions on how to use long focal lenght in this ways.....
Bye

Denny

I often use the 70-200 lens on my Canon 1v to snap close-ups of people working, various goods in markets and such.

I also find it to be a very good addition to my 24-105, which can take broader shots of groups of people and architecture while walking around.