Passover 2015 begins at sundown, Friday, April 3rd, with the first Seder, so you still have some time to send Passover cards to family and friends. Send FREE virtual greetings for Pesach courtesy of Chabad. There are virtual cards suitable for children, for grownups, even an invitation to join your Seder. As I said, free.
Passover continues for eight days and ends at sundown on Saturday, April 4th. Once again, that means Passover 2015 overlaps with Good Friday and Easter Sunday.
The Chabad website also has a list of local Seders to attend nationwide. Here is the link to New York City seders at synagogues and community centers.