ATLANTA — Chicago-based Seyfarth Shaw will lease 84,000 square feet and The Boston Consulting Group will lease 37,000 square feet in the 12th & Midtown office tower in Midtown Atlanta. The two leases represent the first announced tenants in the 725,000-square-foot building, which is being constructed to LEED standards at 1075 Peachtree St. The structure is part of a $600 million, 1.4 million-square-foot development. Delivery of the property is expected in early 2010. Terms of the leases were not announced.