There is also a wealth of information on
the man in seat sixty-one's site, which although doesn't give full timetables, and doesn't actively suggest the route you are planning, will provide you with information about a lot of the remaining sleeper services (if you intend using them), including facilities and tips, as well as more general information about how to navigate the disparate rail systems across the continent.
As with Marklund above, you cannot beat the DB planner for timetable info, although I don't believe every state railway puts their engineering work timetables in to the DB planner (the UK doesn't, for example).