With that I realize part of my fun comes from the accumulation of time spent. It's one of the reasons trying to jump into another aged MMO is difficult. If I join Everquest2 right now everyone around me has books with chapters full of experiences, libraries of books for some.
I have/had that in WoW. I've either shared experiences with people I've played with a long time or I am able to nod knowingly when I meet up with players I just met and they discuss old times.
As soon as you take a break from the game you're immediately out of the loop of gathering these experiences. This makes me feel like I should play all the time. Several times through the years I've found good "stopping points". Places where I felt I could say "now that I've done that I can take a break". I've also come back to the game to regret the breaks (missing out on feat of strength type deals). If your fun is a sum of your activities, your only option is to not take breaks!
All I can do is come to grips with no time would be perfect. This time is as good as any. Inevitably there is always a new carrot swinging around.
If I decide to come back again I'm faced with knowing I've missed out on some things I can't replace. It's a disappointing feeling and makes me not want to come back knowing I'll have these gaps. Ironically it works out better for me in the end.
P.S. I've taken the step of actually canceling. Funny thing is, the first time I tried, the site was down for maintenance. But it didn't give that specific message. Instead it said something like "Oops".
As if it were saying You don't really mean to cancel!!!". Undeterred, I was able to log on later and do the dirty deed.