Similar to SelectMany method, only projects members

extensions.cs

public static IEnumerable<U> SelectProjections<T, U>(this IEnumerable<T> @this, params Func<T, U>[] projections)
{
    if (@this == null)
        throw new NullReferenceException();
    if (projections == null || !projections.Any())
        yield break;

    foreach (var item in @this)
    {
        foreach (var projection in projections)
        {
            var projected = projection(item);
            if (projected != null)
                yield return projected;
        }
    }
}

usage.cs

foreach (var item in persons.SelectProjections(person => person.FirstName, person => person.LastName)
    ;