I wrote a blog article that discusses Community Wiki.
You should never make a question Community Wiki just as a means to avoid closure. Community Wikis purpose is enhanced editing, not an enabler. If you want to avoid closing a question, fix what problems it has. The ideal question to keep is one where you don't have to even think about considering Community Wiki.
If it's valuable enough to stay, it should be a part of the site like a normal question. If it isn't valuable enough to stay, it shouldn't be on the site. There are times where it may work to have a community wiki question - these are few and far between, and are exceptional circumstances. And, moreover, what makes them acceptable won't be the Community Wiki status.
Essentially, if you're thinking about whether a question belongs, don't put Community Wiki in the equation. Community Wiki matters for collaboration - it should be used expressly for that purpose. And honestly, that happens generally only in answers, not in questions.