We present a progress report on studying S-duality in lattice N=4 super Yang-Mills. This is being done through a computation of 1/2-BPS states on the Coulomb branch, especially the 't Hooft--Polyakov monopole and the W boson. Key to these calculations is the use of twisted and C-periodic boundary conditions. In addition we describe a variational method to disentangle operators with definite scaling dimension, particularly the Konishi and supergravity operators.