As a mechanical engineer in the power generation industry, here is my perspective. I have worked in a nuclear power plant, in a capital projects group (split 70/30 between combined cycle projects, and environmental projects and reliability/capital replacement projects), and now at a large district energy plant. All three roles I enjoyed for different reasons and learned a lot at each one. My main objective was to work as little as possible while making the most money possible. I know, that may sound like I am a slacker but let me explain further. Each of those places saw my capabilities and all three wanted me to move up the ladder. I considered my options each time, but in the end, I didn't want to screw up a good thing. As an individual contributor, I always had my work/projects well under control. That meant I had my schedule well under control (with an occasional extended day for an emergent issue, but those were/are rare). I already made good money and had good quality of life. I get to spend plenty of time at my kids activities, working out, etc. Personal well being is more important than a job title and money. Why throw away what I already had for a few extra bucks and a lot more time commitment?
I also highly agree with Greg, you have to look at it as a series of jobs. Be prepared to move on from a company at any given time. I always keep my eye on the job market, and suggest to others to do the same. You don't know when a company will make personnel moves, realign organizations, or fold up all together. In my opinion, it is better to strike first. If the risk is there, move on while you can.