Kurt and others,
 
While I certainly can not guarantee that the gulls will be present this weekend, I think the chances are very good.  I would say that your chances of seeing Little Gull are much higher than for Black-headed Gull.  Including PA, there are between 10-15 Little Gulls on the Susquehanna right now and they will probably continue through the first week of April.  The gull turnover here is quite large and it would not be surprising to see different gulls throughout the day.  
 
Bob provided directions to Lapidum, but I can also give directions to viewing areas in Port Deposit.  As Bob said, most of the gulls are on the Cecil side of the river.  From 95, take Rt. 222 North into Port Deposit.  Turn left just before the large condo buildings and follow parking signs for the Portside Grille.  They have a gravel lot on the south side of the restaurant.  There is a walkway behind the condos which has a bit of elevation to that provides excellent viewing and the residents are very friendly.  
 
As a general rule, I go to Port Deposit in the morning and Lapidum in the afternoon to take advantage of the better lighting conditions.  
 
Matt Hafner
Bel Air, MD