Just wanted to add one more thing. A few have mentioned keeping a rebuildable atomizer around as a backup, and while it's good for that purpose there are better reasons.
1) you know what's in there. No vaping solder or other 2nd rate materials. YOU control what's in your atomizer. I am using kanthal for my coil, .999 fine silver (no reactivity with juice) non-resistance wire and an almost impossible to burn braided ceramic wick (some use stainless steel even). I can't even begin to describe how good my juice tastes with components like this, not to mention I'm not worried about inhaling god knows what (primer, solder, burning fiberglass, etc).
2) Cost. Even using the highest end internals a rebuild costs me 1/10 what an atomizer would.
3) Longevity/reliability. See above, regarding high end internals. They don't just produce great flavor, but they last. I've yet to pop a coil, and I've done plenty of long dry burns to fry off juice.
4) Customization. My last atty I metered at 1.1 ohms and it hits like a freight train, try finding someone who'll sell you a 1.1 or a 2.3, or a 3.9, or a...you get the idea