I don't see the Do Not Disturb option in Messages anymore, how can I stop a thread from notifying me every time somebody sends a text?
For reasons unknown, iOS 11 has changed "Do Not Disturb" to "Hide Alerts." Its function is identical, so no worries, you can still silence annoying conversation threads. Simply tap the Info button in the top right of a thread and toggle on Hide Alerts. iOS 11 is still in beta at the moment, so this change may not stay.