Back in the day I wore 501s all through high school and into my early 20s.  The past 20 some-odd years I went for more relaxed fitting jeans as the styles changed.  But I've been unhappy with my most recent Hilfiger jeans, too binding.  Coincidentally I ran into some Levis shorts that had stretch in the fabric - they're awesome, look and feel like normal shorts but they stretch instead of bind, very comfortable.

I learn that Levis started offering versions of their classics with stretch so I decided to revisit the 501, trying the stretch version.  Key details.

- 501s use a button fly.  Pretty easy once you get the hang of it but they work better if you wear your jeans beltless, zippers work better with a belt.
- 501s sit at the waist, not below the waist.  I like this but YMMV.
- 501s are "standard fit".  This leaves a little room in the seat and thighs but not a lot.
- 501s are straight leg.  That looks better with boots than tapered leg with boots.
- Though the version I got are with stretch, they seem less stretchy than the shorts and some other Levis jeans I got that have stretch.  I do not know why, perhaps I got an earlier year's production and they increased the amount of stretch since?  Or they're all like that?

In general I found these to be an improvement over the binding jeans I've worn recently but I still preferred a little more room.  I ended up going with the Levis 541.  They are similar to the 501 except they are "athletic fit", meaning more room in the seat and thighs and they use a zipper instead of a button fly.  The pairs I got also seem to have more stretch to them, too.  The 541 have worked perfectly for my needs.