Mirtazapine is very effective for sleep too, so you may want to consider it too. It doesn't cause addiction and has virtually no dangerous interactions with any drug. I like the sleepiness it produces, it's a warm and soft, cozy grogginess that nicely puts you to sleep.
Seroquel, well, I was on it for 3 years to get sleep but it's a horrible, horrible drug. It makes you feel like someone's hit you with a brick in the face, and the first weeks you're a walking zombie. You really don't get any tolerance to it and it's not addictive either, so maybe 25-100 mg for sleep could work for you. For me it clogged my nose completely, I had to use nasal spray to be able to breath with my nose when going to sleep.
Of all the meds mentioned in this thread, mirtazapine would be the one that does the least harm to you and the safest too. And it's effective, very much so, for sleep. Withdrawal is nowhere near as bad as with traditional SSRI's. I'd say it's very easy to come off it.