Hello! I think there are many reasons you could appeal to different demographics for a mid week stay so you could try targeting based on peoples travel reasons… maybe a dedicated workspace and local places to eat would bring in people on a work trip ( just an example)
but use whatever reasons folks might visit your area… or perhaps holidays/ events etc
also as someone else suggested try dynamic pricing for mid week bookings- it might simply be down to volume of listings in your area and how prices compare. People always love a deal if you can accomodate that… Just my two cents!