Polymer electrolytes are an important class of ion conducting materials critical to enabling various electrochemical systems. Fundamentally, ion-polymer coordination, inter-connectivity of solvation sites, and corresponding ion-solvating polymer dynamics are critical in understanding the limits of ionic conductivity. Here, the importance of these effects is highlighted in a series of combined experimental and computational studies on model lithium-ion conducting polymer electrolytes. First, we focus on graft polymer architectures of poly[(oligo ethylene oxide) methyl ether methacrylate] (POEM) varying oligo side-chain lengths. With addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), the observed differences in ionic conductivity between the POEM derivatives and linear poly(ethylene oxide) (PEO) cannot be adequately explained by differences in Tg. Instead, graft architecture of POEM leads to nonuniform, position-dependent relaxation and ion solvation behaviors along the side chain. Importantly, the limits of ionic conductivity are dictated by the segmental mobility of the ethylene oxide units that form effective solvation sites, rather than system-wide dynamics. Lastly, the talk will end with results from ongoing work focusing on solvation site formation and ion transport mechanisms in mixed polarity copolymers based on POEM and poly(glycerol carbonate methacrylate) (PGCMA).