Trip planning - Yellowstone after Labor Day

I backpack with a group of guys and a couple of us fish too. None of
us have been to Yellowstone (except for family trips as kids) and are
looking at hinkng/fishing spots Labor Day week. We are getting
old/soft and like to base camp in the backcountry and hike/fish from
there. It appears there are day limits on many camp sites, so we may
have to change our ways.

Any recommendations would be greatly appreciated. It clearly is a
huge place and I am having problems evening knowing where to start. FF
book recommendations apprecitated too.

Thanks,
Barry