In this paper we develop a set of interconnect delay estimation models with consideration of various layout optimizations, including optimal wire-sizing (OWS), simultaneous driver and wire sizing (SDWS), and simultaneous buffer insertion/sizing and wire sizing (BISWS). These models have been tested on a wide range of parameters and shown to have about 90% accuracy on average compared with those from running complex optimization algorithms directly followed by HSPICE simulations. Moreover, our models run in constant time in practice. As a result, these simple, fast, yet accurate models are expected to be very useful for a wide variety of purposes, including layout-driven logic and high level synthesis, performance-driven floorplanning, and interconnect planning.