It could be the biggest all-female tour since Lilith Fair. Billboard reports that Beyoncé, Alicia Keys, and Missy Elliott are in final negotiations to put together a concert triple bill. The tour would take the three R&B/hip-hop divas to arenas in about 20 cities this spring. Additional details are still scarce, especially regarding timing. Keys and Elliott have both been busy in recent weeks with video shoots. Just two weeks ago, MTV News quoted a spokesperson at Beyoncé's label as saying the ''Crazy in Love'' singer was setting aside the entire month of March to record a long-awaited Destiny's Child album with bandmates Kelly Rowland and Michelle Williams. She'll also be seen singing the national anthem before the Super Bowl on Feb. 1 and probably making several trips to the podium during the Grammys on Feb. 8.