Cloud Separation...

In a practical environment, when does cloud separation become an
issue? A few months ago I was passing through the Denver Class B, and
was just above a widely scattered broken layer of clouds. These were
puff balls all within a layer of about 500Ft. Out towards the horizon
they looked like a solid layer, but nearer to me there was probably
only 10-20% coverage.

I debated climbing higher and getting a little more separation between
me and the layer (but that would have required a more rapid decent
later to get into my destination), or decending below the layer (but
that would have taken me out of the Class B and into a very busy VFR
corridor), so I elected to stay where I was.

Visibility was excellent, but I was passing pretty close to some of
the cotton balls. Should I have gone to a different altitude? Which
way? I wasn't assigned an altitude by Center, but should I have told
them I wanted to assend or desend and get their recommendation? Do
you all avoid any and all clouds, or just the big ones that will
interfere with trafic spotting and visibility?

WW