Auto-suggestion is a tricky animal. Unless there's a very good reason to use it, I generally avoid doing so as evaluating and eliminating suggested choices generally ads to a user's time to task completion and interaction costs.
The big question you need to ask yourself when deciding whether or not to implement an auto-completion/suggestion system is whether or not your users will be able to come up with useful queries on their own. If your system can be designed to suggest better or more effective queries based off user input, then it's perhaps worth spending the time to engineer. Otherwise, you're needlessly adding to interaction cost without any real benefit.
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