I thought I'd try these T-shirts out, being unhappy with the cheap & thin Hanes Beefy-Ts I got online.  Since a lot of reviewers said the sizes of these ran small, I ordered one size larger than normal.  Man, I don't know what the other reviewers were talking about.  These are huge!  In fact the label says "Relaxed Fit", which is jargon for bigger-than-usual.  Any other manufacturer's large shirt just barely fits me, but these in XL can take a whole 'nother one of me inside.  Other than my ordering the wrong size, the fabric is indeed heavy & substantial, and these are very good quality shirts.

Ok, I just received my order of shirts in the correct size, large.  They're perfect!  Just the right amount of slack and the tail of the shirt is extra long - goes about 10" below my belt line.

Update August 2013... Now that I've worn these for 6 months, I would have to make this important observation.  The elastic in the neck will sag after just a few washings, making you look like a hillbilly.  If you don't mind this backwoods look, then have at it.  Most people would care, though.