This got me wondering about what commonly-used words are the longest for each row. In addition to "typewriter", other 10-letter words you can type exclusively on the top row include "perpetuity" and "repertoire". Claims for "teeter-totter" seem to be cheating, as it is almost always written with a hyphen. The OED lists a few more such words, but none that are common ("pepperwort"?).
For the middle row, the longest seems to be "alfalfa".
The poor sad bottom row seems to have no examples at all, unless you include "zzz", which is sometimes used to indicate the sound of sleep.
On a French AZERTY keyboard, one can type the English words "appropriate", "perpetrator", "preparatory", "proprietary", as well as the winner, "reappropriate". The longest French words on their national keyboard seem to be "approprieriez" and "pirouetterait".