A few unavoidable times I've been without my electric for a week or so, maybe more... but I haven't gone a day since I first started playing the guitar about 2 years ago without laying my hands on some type of guitar.

When I don't play I usually feel guilty... kind of the way pro runners feel guilty when they don't run. As for addictive, well, some people have addictive personalities and are easily addicted to things. Anything can be addictive. There are much worse things to be addicted to then playing the guitar imop.