April is a beautiful time of year to visit Lancaster. I second the vote for Burkholder's; it's in the middle of nowhere in a cornfield and it's a totally awesome quilt store. The Old Country Store in Intercourse is good too. If you're willing to travel a bit, Lititz is not too far from Lancaster and Wilbur Chocolate and Sturgis Pretzles are both in town, old fashioned factories that do tours.
If you're into Outlet shopping, Lancaster has a bunch all in a couple of strip malls on the eastern side of town. Lancaster County is beautiful; you'll enjoy it! Take care on the roads and watch out for buggies and people passing same.