Thanks again.
You know how you could really thank everyone who has contributed? Give each and every submission your honest opinion as if you were a client and you went to their office and they submitted this as an idea for a logo. That would complete the real world experience.
Be as blunt as you would be in real life. But do remember the usual way to submit logo ideas when the client has been as vague as you have been is to submit something, anything to try and get a feel of how the client is thinking.
For example if you give no indication then no one is going to want to follow up. If, I respectfully suggest, you just say 'thanks and goodbye' then you have wasted everyones time, the thanks become hollow. So tell us how crap they really are, we're all big boys and girls.