GMC and Chevrolet are pretty much the same truck. Both made by General Motors. Ford has just introduced a new line of "Transit" vans, and Nissan also has commercial vans that would meet your need.
More recently it has sired a family of variants that now include the GMC Yukon/Denali XL, the shortened Chevy Tahoe and GMC Yukon/Denali, the upscale Cadillac Escalade (coming soon in stretched Escalade ESV trim), and even the highly altered Hummer H2. Together, the Suburban and its offspring snag 63 percent of the full-size-SUV market.