In this work, we conduct a throughput-cost study of several optical network architectures: optical flow switching (OFS), tell-and-go (TaG), electronic packet switching (EPS), and generalized multiprotocol label switching (GMPLS). The simple, multi-tiered optical network that we consider comprises two groups of users, each in a distinct metropolitan-area network (MAN), which wish to communicate over a wide-area network (WAN). Our network cost model focuses on initial capital expenditure: transceiver, switching, routing, and amplification costs. Our results indicate that: OFS is the most scalable architecture of all, in that it is most cost-efficient when the average user data rate is high and the number of users in the network is large; EPS is most sensible when the product of the number of users and the average user data rate is low; the GMPLS architecture, which is conceptually intermediate to EPS and OFS, is optimal when the product of the number of users and the average user data rate is moderate; and, finally, there does not exist an optimal regime for TaG.