I keep meaning to put this pic up, and now I finally remembered where I stashed it on my computer.
For scale, the superimposed hexes are the equivalent size to BT hexes. The people in them are, in scale, the same size at BattleMechs. Or, for those of you with a more SAT bent, "Pictured People : BattleMechs :: Pictured Hexes : Mapsheet Hexes"
Mechs don't take up very much of a given hex, so the next time you're saying, "oh he's right next to me, I can do 'X thing', think about this image. That prone Mech may be on the far size of his hex, and you may be on the near side of yours.