Update 12/17/13: The 50k mile offer on the Lufthansa card is dead.

The 50k mile bonus offer is back on the Lufthansa card mentioned in this post until 6/30/14.

The American Airlines Explorer Award is an incredible use of miles. An Explorer Award is a distance-based award that allows multiple stopovers, so it's a versatile award perfect for globetrotters on round-the-world itineraries or cramming many trips onto one award at a steep discount.

I want to illustrate how a relatively simple award routing to Europe can also be a great use of an Explorer Award by saving miles and adding free stopovers that wouldn't be permitted under normal circumstances.

I'm planning a trip to Sofia, Bulgaria this summer and uncovered a great value.

United, Lufthansa, US Airways, Air Canada, ANA, Singapore, and TACA/Avianca are all members of the Star Alliance.

With few exceptions, all of their miles can be used with equal access to any Star Alliance carrier's Saver award space.

You cannot transfer one type of miles to another. For instance, you cannot transfer your Lufthansa miles to your United account.

But you can combine the power of your miles by using miles from several different accounts to book awards on the same flight.

I've written several posts about Explorer Awards from American Airlines. My favorites are:

American Airlines Explorer Award: The Rules
The Start of My Anatomy of an Award Series on a Real Explorer Award: Planning a RTW Trip
My Post about Getting the AA Miles Needed for a Business Round-the-World Trip

American Airlines Explorer Awards are by far the cheapest option for round-the-world awards and a great option for hopping around one part of the world with many stops.

Explorer Awards are also incredible for combining many trips onto a single award at a huge discount.

Our Award Booking Service has been rocking and rolling lately. Busy frequent flyers love the personal attention we give each itinerary, as well as our expert knowledge of award programs.

The MileValue crew has a battle-tested recipe for award booking success.

US Airways has announced its plans to leave the Star Alliance for the oneworld alliance and later merge wither American Airlines.

But for the time being US Airways is in the Star Alliance and its miles can be used on its own flights or its Star Alliance partners.

At least in theory.

In practice, for the past few months US Airways agents have not been able to see award space on Lufthansa, the Star Alliance airline that releases the most space between the US and Europe.

You could find award space on united.com, call US Airways, and the agent would

While booking a family of four to Australia through our popular Award Booking Service, I ran into a  vexing problem with Star Alliance award space.

On a certain Air Canada route, Air Canada's own Aeroplan members  had access to more award seats than its Star Alliance partners. That's not a surprising practice on the surface. Air New Zealand never releases transpacific space to Star Alliance partners.

Mashable readers: Welcome to the best blog on redeeming frequent flyer miles. The way that I've traveled to over 20 countries this year and spent nine months abroad is by signing up for credit cards and using the miles to book business and first class awards.

Here is a post that explains to beginners what I do and why I do it.

Mashable readers: Welcome to the best blog on redeeming frequent flyer miles. The way that I've traveled to over 20 countries this year and spent nine months abroad is by signing up for credit cards and using the miles to book business and first class awards.

Here is a post that explains to beginners what I do and why I do it.