I've got a few instruments around my place, and others that are "out on loan" to friends and family. All completely justified - they're in no way an indulgence! Hahaha
However many basses / guitars you have, there's always a hankering after "the next one".
As for tweaking the instruments, I adjust the truss rods when required (usually due to the summer and winter climate differences), and clean the fingerboard each time I change the strings.
Does anyone else do the "clean the dust out from under the strings" thing on a regular basis? - where you use a cloth to wipe away the dust on the scratchplate / body under the strings area?