Using async/await for multiple tasks

I'm using an API client that is completely asynchrounous, that is, each operation either returns Task or Task<T>, e.g:

static async Task DoSomething(int siteId, int postId, IBlogClient client)
{
    await client.DeletePost(siteId, postId); // call API client
    Console.WriteLine("Deleted post {0}.", siteId);
}

Using the C# 5 async/await operators, what is the correct/most efficient way to start multiple tasks and wait for them all to complete:

int[] ids = new[] { 1, 2, 3, 4, 5 };
Parallel.ForEach(ids, i => DoSomething(1, i, blogClient).Wait());

or:

int[] ids = new[] { 1, 2, 3, 4, 5 };
Task.WaitAll(ids.Select(i => DoSomething(1, i, blogClient)).ToArray());

Since the API client is using HttpClient internally, I would expect this to issue 5 HTTP requests immediately, writing to the console as each one completes.