Thanks very much to both of you for the info. It really sounds like I could just leave the printer sit for three weeks, whether asleep or powered off, and if there are clogs when I get back they should clear with a normal cleaning or two. I have yet to see a clogged nozzle on the P7000. I previously had a 7900 and had no significant problems leaving it powered off for up to 5 weeks a couple times per year for over 7 years. There would sometimes be clogs when I returned but normal cleanings cleared them without issue. The P7000 should be at least as good.
Something to note about the "Timer Cleaning" function, which I investigated endlessly:
The printer does
exactly what the manual says it will do, specifically: "Performs an automatic nozzle check and head cleaning if the printer is
turned on or
woken from sleep mode and the printer has not printed within the set length of time."
1. The printer does not wake itself from sleep or power off under any circumstance I've been able to test, regardless of settings and whether or not paper is loaded.
2. If the printer is powered off and the set amount of time has elapsed it will check nozzles
when it is turned on. A person must obviously be present to turn the printer on.
3. If the printer is asleep and the set amount of time has elapsed it will check nozzles when it will check nozzles
when the next print job is sent. A person must be present to send the print job unless you have a scheduled task do it automatically, which is what I have been thinking about doing.
The Epson SC P7000 (and certainly the P9000) printers apparently do not have the ability to automatically (without help from a computer and a scheduled task) maintain their nozzles. That is contrary to what I have read in two different online reviews, but interestingly I cannot find any claims by Epson that the printer will do this. The closest thing to that I could find is a vague reference to automated cleaning that has no description of how it works. I contacted Epson support and they indicated the only automated cleaning function is the Timer Cleaning Function, which works as described above. It has its place but is definitely not a "keep the nozzles clear while I'm away" function.
See also
http://forum.luminous-landscape.com/index.php?topic=111547.0