The BSO program detail page describes the opening night program as follows:
Celebrated soprano Renée Fleming opens the 2014 BSO season at Tanglewood in an all-American program. With the Boston Symphony, she will present great works of the American concert hall and opera stage, plus favorites from musical theatre and popular genres.(Emphasis added)
The program detail page has links to performer bios (click on the pictures) and program notes Composers are Schwantner, Copland, Barber, Adams, Gershwin, and Rodgers, conductors William Eddins and Rob Fisher.
The page for Sunday afternoon has this to say:
Jerusalem-born conductor Asher Fisch leads a Romantic program fitting for a mid-summer Berkshires' evening. "I've just finished a tiny, tiny piano concerto," Brahms wrote to a friend, referring with great understatement to his piano concerto number 2, a piece as expansive and passionate as a symphony and as intimate at times as a string quartet, and performed alongside the BSO by the magisterial American pianist, Garrick Ohlsson. The preface to the score of Liszt's Romantic symphonic poem Les Preludes reads, in part, "Love is the enchanted dawn of existence," a sentiment echoed in the closing excerpts from Wagner's sunniest opera, Die Meistersinger, a tale of love fulfilled.(Some emphasis added, and editorial corrections made)
Go there for the usual links, including an audio preview of the Brahms.
As usual, it's all available approximately live on radio and over the web via WCRB. Their BSO page has the whole Tanglewood season broadcast/webstream schedule, as well as links to an interview with Miss Fleming and lots of other things (including recent Pops concerts).