I have a partial view that has something like this
<%= Html.DropDownListFor(m => m.SelectedProductName, Model.ProductList, \"Select a Product\") %>
I can't find the documentation at the moment, but there is an overload for DropDownListFor that will accept an object-typed collection of attributes (HtmlAttributes is the parameter name.)
It will look something like this:
Html.DropDownListFor(model=>model.SomeProperty, new {@id="UniqueID1234"});
You can use Intellisense to find the overload that includes HtmlAttributes.