Big companies like Boeing are killing the marketability and the salary of engineering fields.
To be more marketable anywhere - get your PE. This could be difficult due to the work requirements. It is worth the effort.
Product design is very cool stuff, but it's like architecture. It's hard to break in to and when you do get there, the pay sucks for a while since it is such a desirable field.
Manufacturing is less glamorous, but there are lots of opportunities all over the world with all of the automation going on. Same goes for machine design.
Hours, work environment, etc all goes with where you are working, not the job.
Long term prospects are varied but usually come from the larger companies/firms. These are the places where the work will (generally) be less interesting.
If you chose to contract you will make good money with an uncertain future. Contracting is a good way to open doors and gain experience in multiple areas while you are younger and less worried about health issues and retirement.