I got my ISSA cert before I did much research on what gyms looked for. I just studied once in a while until I got through the book, but I'm a bad reference, I retain stuff I read really well, I've never really had to study.
I'm not sure why anyone hiring trainers even cares about certs, most of them are meaningless.
I've found that training is one of those jobs where you've got two options: either the pay is good and the hours suck, or the hours are decent and the pay sucks.
Try to stay away from commercial gyms. They take most of the money that you bring in for them, and they're always full of politics and backstabbing.
Best bet is working for a small private gym, or working on your own. I don't know about ACE, but ISSA was all set up to help get your small business stuff and insurance.