The continued drive for increased performance and higher engine efficiencies has seen the adoption of thermal barrier coating technologies as an integral part of modem engine design. Future engines will require even better performance from such thermal barrier coating system, towards the ultimate goal of "designed-in TBC's". This paper reviews the advantages and disadvantages of various TBC systems, with the aim of custom designing a thermal barrier coating system to have good strain tolerance and low thermal conductivity. The influence of coating microstructure on the coating thermal conductivity and strain tolerance is discussed, and it is shown that by advanced processing it is possible to deposit EB-PVD coatings with thermal conductivities of 1.0W/mK, much lower than current commercial EB-PVD coatings at 1.5-1.9 W/mK and closely matching that for plasma sprayed ceramics (0.8-1.1 W/mK).