We worked around all of these issues by going to the aquarium late in the afternoon (tickets are half off during the last hour); there was no line to get in, we found an hour to give us plenty of time, and the crowds weren't too bad.  Did this twice last year, and had the same result both times.

Related bargain - Fulton county residents get free admission to the Atlanta Museum of High Art every first Saturday of the month.  Drawback is that it brings in huge crowds (although we found the best parts of the museum, deeper in, virtually empty).

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Sweater, n.: garment worn by child when her mother is feeling chilly. ~Ambrose Bierce