I've been suggesting that the earlier dates (May, June, early July) are a bit better, but only for purposes of reliable weather. After Mid to late July, the wind can begin to pick up a bit, and the calm sea conditions needed for a great kayak trip aren't as easy to predict.
As far as wildlife goes, any time is a great time... If you're out in July or early August, keep your eyes open for deer roaming the beaches at low tide. Otherwise, whales, seals, sea lions, eagles, etc. are out all the time...
Happy Alaska Travels!
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