It looks like I found some available quests in the high teens. One called "Delerium" in the enclave of The Twelve I tried on normal at level 15 and was wiped out by a Beholder boss. I'd like to try it with help on elite at level 18. Also I have the Vale of Twilight adventure pack which would be 7 quests at level 17/18 on elite.
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Unfortunately it looks like there was a patch yesterday and the login server is down, hopefully will be fixed by tonight.