Since US Airways joined the oneworld Alliance on March 31, I think they have the most valuable miles of any airline. The three main reasons:

The world's cheapest award chart.

US Airways joined oneworld today, March 31, 2014.

US Airways leaves the Star Alliance Sunday (3/30/14) and enters the oneworld alliance Monday (3/31/14) as part of its ongoing integration with American Airlines.

Overall, this news is mixed because some awards are more easily booked with Star Alliance partners and other awards are more easily booked with oneworld partners.

Here are the awards that are easier to book in the next two days and the awards that are easier to book next week with US Airways miles.

One partner that US Airways loses on Sunday is Lufthansa, the German flag carrier, which is currently offering incredible summer award space

On the US Airways award chart today, I noticed a minor change as part of the US Airways / American Airlines integration.

Did you catch it?

On the US Airways chart, the word "Envoy" has been replaced with "Business Class."

US Airways had previously referred to its International Business Class as "Envoy" (and it still does on other pages), but it looks like that name will disappear during the integration.

This is semantics, since the Envoy / Business Class will still be a great product--at least on the A330s where it is completely flat--but a far bigger change is coming

US Airways Premier World MasterCard with 40,000 bonus miles after first purchase to book these Star Alliance and oneworld partners

Earn 40,000 bonus miles after your first purchase and payment of the $89 annual fee*
First checked bag FREE on eligible bags for you and up to four companions on domestic US Airways operated flights
One companion certificate good for up to 2 guests to travel with you on a US Airways

Per the email I received last week, US Airways is again offering up to a 100% bonus on purchased or gifted miles. This "Mystery Bonus" promotion is a slight variant from previous iterations, as the bonus you receive varies by individual frequent flyer account. You might receive a 25%, 50%, 75%, or 100% bonus on purchased and gifted miles.

US Airways frequently runs promotions offering bonuses to buy its miles, including one in December of last year. The deal is hardly a new proposition, especially if you receive an inferior 25%-75% offer like I did.

Come to Happy Hour with me today (2/17/14) in New York City!

US Airways has legally combined with American Airlines, but the airlines are still being run as two brands with two frequent flyer programs until some time in 2015.

Next month there are two key dates in the integration of the two airlines and specifically their AAdvantage and Dividend Miles programs.

On March 30, 2014, US Airways will leave the Star Alliance. This is the last day to use US Airways miles to book award space on Star Alliance partners. (Actually see this update.

For flights between the US and Europe, Austrian Airlines releases its economy class award seats to partners 298 days before the flight and its business class award seats to partners 88 days before the flight.

Austrian routes between the US and Europe have economy award space up to 298 days out

Austrian is a Star Alliance member that operates five routes to North America from its hub in Vienna:

New York-JFK
Chicago
Washington-Dulles
Toronto (don't forget about routing to Europe via Canada)
Newark (begins July 2, 2014)

Austrian operates two cabin Boeing 777s and 767s

All Nippon Airways (ANA)--a Japanese Star Alliance carrier--launches a new route between Tokyo-Haneda and Vancouver from March 30, 2014.

Saver award space is excellent on the route in economy and business class. You can book the space this week--by January 31, 2014--with United miles at pre-devaluation rates.

The offers for the cards listed in this post have expired, so their links have been removed.