I'm a mechanical engineer who really enjoys her job. I'll second the suggestions to look for a school with a solid co-op program, and to consider taking engineering technology if there is concern about debt load or time out of the work force. Many universities will accept college programs in eng'g tech as partial credit towards a degree if you decide later to go the degree route.
Of course check out some job descriptions that are targeted toward eng'g techs vs. engineers, to see if you might enjoy work in one field or the other. Ultimately what's important, especially with the time and $ commitment of going back to school, is picking the thing that will be the best fit for you.
Definitely look into scholarships for women in non-traditional careers, and for mature students. Some banks have very generous repayment terms for student loans, and if you live in Canada there is the possibility of government loans. Most student loans require you to pay only the interest while you're in school, and you do not begin to pay back the principal until 6 months after you graduate. Usually student loans have the lowest interest rates, but you might ask your bank about other options, like a huge line of credit. With the prime rate as low as it is, right now might be a fantastic time to pursue something that requires a major financial commitment. (Which leads me to wonder why I'm still not going after a pilot's license, but that's my problem.)
Engineering WILL require a huge amount of your time, especially if you are a full-time student. Although eng'g jobs are generally very family-friendly, getting the degree is NOT. If you want it badly enough, you'll find a way to do it, but be prepared for it to be a rough ride. I'm not saying this to discourage you, because I think engineering is awesome, but just as a reality check.
Having said all that, it has definitely been worth it because I really like my job. (Most days.
) You're right; there are lots of different opportunities and lots of different career paths within engineering. I love being involved in something "real," like you said, and I love the feeling that my work is going towards the greater good.