Hey Libelle,
Speaking from experience, I was always curious about evolution at school. I was told to block out what the teacher was saying during history/humanites lessons. I think that had I actually learned the whole truth about evolution from a young age, I wouldn't have swallowed the WTS bull. I would say teach them a lot about science, anthropology and evolution. I realise this ain't gonna happen if you want your kids to develop some kind of spirituality. My take on it is this... let your kids be kids, and when their mind is mature enough and serious enough, then they will be able to explore a spiritual belief, or disbelief. My view is that the WTS is so dangerous, I would willingly sacrifice them actually having any kind of spiritual belief, rather than have their life screwed up by a dangerous cult.
Maybe you will now have to show them the way. Teach them that it's okay to question anything...not just religion. Teach them how science developed over the years... How the catholic church opposed the great thinkers like Galileo etc. They will soon draw conclusions that an organization can be closed-minded, obtuse, just plain wrong. They will see parallels with the way the Watchtower operates.
Maybe you could get interested in nature programmes? A lot of them are slanted towards modern scientific thinking. Even if it's not your 'bag'...you're gonna have to make it so. When you watch TV as a family, it's an excellent way of subtley influencing their thinking. Your kids may well find an interest in it too, if they see you are enjoying it. My mother especially hated anything nature/science related, as she said it was all satan's propaganda and lies.
Good luck. You're gonna need it!