A colleague who's managed several enterprise projects shared a guide that helped me understand the landscape of larger agencies. It profiles firms like AKQA with 3,000+ people across 29 locations, Code & Theory with 1,000+ team members, and even mid-sized players like Clay with 70+ professionals. What I found useful was the breakdown of what each size tier actually delivers global reach and deep resources versus agility and personal attention. The section on largest web design companies includes practical details like minimum investments ($250k for the biggest players) and what they're not ideal for, which helped with realistic comparisons. It also covers boutique options that punch above their weight for companies not quite ready for enterprise scale.