I have a Canon 550D, with the kit lens EFS 18-55mm IS, an EF 100 mm Macro, and an EF 70-200mm IS f4.0 zoom. I also have access to an older 17-85 mm IS lens which I quite like, but it suffers from lens creep - if that is the right term....the lens extends when the camera is being carried but not in use.

I am wanting to purchase a good quality general purpose walk around lens, that will stay on the camera most of the time. It would be used mainly for everyday shots, landscapes, and holiday pictures. As a relative newcomer to the the world of DSLRs there is a huge and rather confusing number of lenses from which to choose. I would prefer Canon or Sigma brands, and would be really interested to hear what you folk might suggest, and why.

Many thanks in anticipation.