In this AWS re:Invent 2023 session, Bill Tarr from AWS SaaS Factory discusses common architectural pitfalls in building multi-tenant SaaS solutions. He covers key challenges including deployment strategies, noisy neighbor issues, cost management, DevOps practices, and customization vs. configuration. Tarr provides practical advice on avoiding these pitfalls, such as using flexible deployment models, implementing tenant isolation, focusing on unit economics, automating operations, and leveraging configuration over customization. The talk emphasizes the importance of continual optimization and testing to build scalable, cost-effective SaaS architectures. Viewers will gain insights into best practices for designing and operating SaaS solutions on AWS.