Honestly, I never had a problem with my 9600 even after it sat for a couple of months, it would still throw out a good print with no clogging from sitting turned off.
Now, my 9900... that thing would get partial clogs just looking at it and finally had a stroke in the green channel with a complete clog.
I'd say keep it loaded and just throw a small image thru it once on a while. Maybe switch it over to B/W printing.