In recent years there has been a proliferation of research on a number of wirelessmulti-hop networks that include mobile ad-hoc networks, wireless mesh networks,and wireless sensor networks (WSNs). Routing protocols in such networks are oftenrequired to meet design objectives that include a combination of factors such asthroughput, delay, energy consumption, network lifetime etc. In addition, many modernwireless networks are equipped with multi-channel radios, where channel selectionplays an important role in achieving the same design objectives. Consequently, addressingthe routing problem together with cross-layer adaptations such as channelselection is an important issue in such networks. In this work, we study the jointrouting and channel selection problem that spans two domains of wireless networks.The first is a cost-effective and scalable wireless-optical access networks which is acombination of high-capacity optical access and unethered wireless access. The jointrouting and channel selection problem in this case is addressed under an anycastingparadigm. In addition, we address two other problems in the context of wireless-opticalaccess networks. The first is on optimal gateway placement and networkplanning for serving a given set of users. And the second is the development of ananalytical model to evaluate the performance of the IEEE 802.11 DCF in radio-over-fiber wireless LANs. The second domain involves resource constrained WSNs wherewe focus on route and channel selection for network lifetime maximization. Here, theproblem is further exacerbated by distributed power control, that introduces additionaldesign considerations. Both problems involve cross-layer adaptations that mustbe solved together with routing. Finally, we present an analytical model for lifetimecalculation in multi-channel, asynchronous WSNs under optimal power control.