Okay, I can't sing the praises of my reel mower enough. Granted, if your grass grows 4" while you are on vacation (not a hypothetical, unfortunately) it'll be a pain to mow, but other than that ...
The little snickety-snick as the blades turn and cut the grass. Knowing that you're not going to throw rocks up and hit yourself, your car, the kid next door, the mercedes next door (that is a hypothetical), your kid, your dh (who deserves a rock for not bringing you water as you're out mowing in 95F heat with 99% humidity). Knowing that there's no way you're going to slip and cut off your toe (actually happened to a classmate). Not smelling the nasty smell of gas. Not PAYING for the gas.
This is all priceless. Not to mention (you'll love this) it burns anywhere from 200-500 calories/hour (and if like above, your grass grew 4" since the last time you mowed, probably more like 1000 calories/hour), builds strong legs and arms and even works the ab muscles. AND they cost sooo much less than a power mower.
Plus, it's yet another step towards a sustainable life.