Flat vs Nested ViewModel Classes in ASP.NET MVC

I'm looking for some opinions on two different approaches to ViewModel definition

I have a Company class

public class Company
{
    public string Name { get; set; }
    public int CountryID { get; set; }
}

For the Create and Edit views I need a list of Countries to populate a DropDownList for CountryID selection. I can see two broad choices for how to structure the ViewModel that are detailed below.

Nested ViewModel

public class CompanyCreateEditViewModel
{
    public Company Company { get; set; }
    public IEnumerable<Country> Countries{ get; set; }
....
}

Flat ViewModel

public class CompanyCreateEditViewModel
{
    public string Name { get; set; }
    public int CountryID { get; set; }
    public IEnumerable<Country> Countries{ get; set; }
....
}

At present I'm favoring the Nested approach as it saves me from defining fields for a second time, but I want to throw it open to better approaches and comments.

Thanks