Wanting to get a jump on Spring, but are concerned about the possibility of cold nights still to come.  It's still not too late to plant pansies and violas.  They will give you good garden color and look good until early June.  If you are looking for something to put out now that will look good through the summer, the Wink series of Diascia is a great choice for patio containers.  This will give you a big splash of color through out the spring and summer with minimal maintenance.  Later in the summer this product will require a little shade in the afternoon.  If you are looking for something to put in the landscape for color, petunias, dianthus, and snapdragons will give you color throughout the summer and will take a frost.