ITA's Matrix beta site (http://matrix.itasoftware.com http://matrix.itasoftware.com) does both flexible day and flexible airport for multi-leg trips. To do mul

ITA's Matrix beta site (http://matrix.itasoftware.com http://matrix.itasoftware.com) does both flexible day and flexible airport for multi-leg trips. To do multiple airports, type in the airport codes separated by commas: "lax,sfo".