Though he came by his reputation as one of today's top jazz pianists with a series of albums called "Art of the Trio," Brad Mehldau has been exploring different musical formats lately. His 2010 CD, Highway Rider, augmented the trio with guest stars and a chamber orchestra, showing off his classical influences, while his just-issued two-CD/DVD set, Live in Marciac, is a solo piano performance that's drawing critical raves for its extended display of virtuosity. Now, fresh from shows in Europe — both solo and with Swedish mezzo-soprano Anne Sofie von Otter — Mehldau is reconnecting with bassist Larry Grenadier and drummer Jeff Ballard for some highly anticipated U.S. dates, mostly concerts but also a handful of clubs, including St. Louis' Jazz at the Bistro.