I just posted on one feature that I would like to see in C# 6.0, automatic property initializers. Another that I would like to see is some kind of reserved word access to the automatic backing properties that are created. This would actually allow for more complex property initializer scenarios without actually having to create the backing field.
public IEnumerable<Address> Addresses
return field.Where(x => x.IsActive);
} new Collection<Address>();
This example builds on the automatic property initializer that I have proposed previously but adds a parameter to the get accessor which can then be used to operate against the backing field. The backing field type is determined by the initializer.