Who will Bono invite onstage for a song during U2’s first pair of four TD Garden shows on its Innocence + Experience tour? A U2 tribute band even matched riffs with its Irish rock heroes in Toronto. We’ll find out on Friday and Saturday; U2 has been serving fairly consistent sets with a few rotating nuggets from its early albums and several songs from last fall’s Songs of Innocence and high-tech video walls that even stretch along the floor-spanning catwalk to a second stage. Other Friday shows to consider include Club d’elf with guitarist Van Martin and ex-Zappa percussionist Ed Mann (both seen in this clip) at the Lizard Lounge and feisty scion siren Martha Wainwright at the ICA as part of its Wavelength outdoor shows on the waterfront. There’s also an outstanding Saturday night hip-hop festival at the Middle East with local stars EDO.G, Slaine, Rite Hook, Dutch ReBelle, Termanology, Acrobatik, Reks, STL GLD and Latrell James.

But two festivals also grace this summer’s first seasonably hot weekend. West of Boston, the Green River Festival takes over the grounds of Greenfield Community College, primarily on Saturday and Sunday, boasting an eclectic lineup that includes Milk Carton Kids, Punch Brothers, Rubblebucket, tUnE-yArDs (pictured), Red Baraat and Steve Earle (who moves on to his own Tuesday show at the Wilbur Theatre). Here’s the full schedule. But don’t forget to catch Green River’s signature experience: hot-air balloons that hover at one end of the field around sunset while the bands play at the other end. South of Boston, there’s also the Levitate Music & Arts Festival, a Saturday soiree at the Marshfield Fairgrounds that sports Big Easy favorites Trombone Shorty & Orleans Avenue and Galactic plus Dr. Dog and the Chris Robinson Brotherhood, whose Neal Casal made the intermission music for the Grateful Dead’s Fare Thee Well simulcasts last weekend. Here’s a jump to my recent Robinson interview.

On Sunday afternoon, in a different outdoor context, locally born rock sensations Kingsley Flood and Americana band Parsonsfield play the Rock and Blues Concert Cruise aboard the Provincetown II that leaves from the World Trade Center pier. And Sunday night, the venerable punk band Stiff Little Fingers plays the Sinclair, a rousing end to the weekend, especially if you need an alternate jolt of Irish rock.