Families looking for something special might want to journey to the Barbican where David Greig's adaptation of J. M. Barrie's Peter Pan takes flight (May 2-29). Or maybe a trip to Greenwich for Elephant at the Greenwich (May 20-23). It's a performance piece said to be especially lively. Or still more, The Hobbit at the New Wimbledon (May 4-9), which probably needs no explanation for Tolkien lovers.