Hrm. It appears that I wasn't setting InitialCatalog when building the connection string, at least not in the right place. You don't have to have an initial catalog when testing a connection to a database, which is code near what I'm doing, but you do have to have it to access database tables. I was worried that it was something simple - turns out it was. Upon reflection, I'm kind of glad.

There are times I just use List<> or Dictionary<> when I don't need anything more than that. The main reason I use what I described is that 1) I want to encapsulate the CRUD operations at that level so the item classes are lighter weight, and 2) I want to provide other functionality than I get with List<> or Dictionary<>. I could, and have, used factory classes, but for some reason I am partial to strong encapsulation.