There are few rising R&B stars as stylishly ambitious — and consistently satisfying — as Janelle Monae. Her 2010 album The ArchAndroid explored a futuristic mélange of hip-hop, R&B, soul, and rock — but even its heady conceptualizing couldn't keep hits like "Tightrope" and "Cold War" from inciting dancefloors wherever they were heard. Her new single, "Q.U.E.E.N.," features Erykah Badu, even more sci-fi fictionalizing, and lots of string parts. So perhaps it's not surprising that Monae is the pop star guest at San Francisco Symphony's annual Spring Gala: She's got the classy look, the immaculate voice, and the world-conquering attitude. Her joint performance with the vaunted orchestra this week won't come cheap, but it does promise to present Monae in an unusual setting — and one for which she's uniquely well-qualified.