According to WSJ many urban dwellers including Manhattanites are opted out of the 2nd home in the Hamptons or other beach destinations, in favor of a 2nd home in the very same urban setting. Would you prefer to spend two hours in traffic to only repeat the same about 48 hours later? Would you also opt for a 2nd home a bit closer to home? A couple for example, on the upper east side, buys a 2nd home in the West Village to experience a change of scenario since the two nabes are so different.
As a plus a 2nd home in the West Village will most likely appreciate more than a home in the North or South Fork of Long Island. On the downside of purchasing a 2nd Manhattan home is that most likely it will need to be a condo though some Manhattan co-op buildings do allow 2nd homes or pied-a-terres.