I'm curious about how your players respond to sessions that are mostly planning. When I was running Fixers, my "caper" campaign about an association of consulting criminals, we initially had scenarios where one session was spent investigating and planning, and then in the second session the plan was carried out, and because the characters were experts, most of the plan ticked off like clockwork. And while one of my players loved that, the others found it incredibly dull (the proverbial watching paint dry), to the point where they were ready to abandon the campaign. Perhaps you're handling those planning sessions differently than I do, or perhaps your players are in it for something different than (most of) mine?