Introduction: Modern cloud-native companies (e.g. Airbnb, Netflix) operate complex virtual networks to support global, large-scale services. Achieving scalable, secure, and highly available networking in the cloud requires careful VPC architecture design. This report compares AWS and GCP best practices for Virtual Private Cloud (VPC) networks at enterprise scale. We focus on VPC structure, subnet segmentation, multi-account/project design, shared VPC strategies, cross-region connectivity, service isolation, and secure access patterns, with high-level ASCII diagrams illustrating key topologies.