Prioritize proximity to major highways and rail links, on-site cross-dock capability, bonded and climate-controlled storage, and robust yard management. Verify carrier density for regional lanes and last-mile reach, and confirm WMS/ERP integration, real-time tracking, and SLA-backed transit and order-fulfillment KPIs.

Request detailed cost models that break down storage, pick-and-pack, inbound/outbound handling, and value-added services. Compare historical SLA metrics—order accuracy, on-time shipments, and dwell time—and require sample reporting. Factor in carrier surcharges, customs handling, and returns processing to calculate true cost-to-serve.

Look for scalable warehouse footprint, flexible labor arrangements, peak-season surge support, and technology that enables inventory visibility and automation. Confirm the 3PL's experience with returns workflows, multi-channel routing, and vendor compliance to ensure predictable service levels as volumes grow.