Hottest lady at the gym always flirts with me and smiles and waves across the gym to me.
I have talked to her multiple times. She doesn't really talk to anyone else there. It has been over a year this has been going on.

She is married and her husband works out at different times and works for the law.

Should I even bother asking for her # or for her to hangout sometime?

Hey mate been here before. I'm gonna say be subtle about it if you decide to make a move. A lot of times ppl mistake friendliness for flirting/ioi's. I'd say as your leaving be like hey I'm gonna grab a coffee at starbucks wanna care to join me? Something like that if she says yes then talk over coffee see where it goes from there. If she says no all you did was invite her out for a coffee nothing for her to be mad at nothing to cause any awkwardness. I say be subtle setting it up, but once its set up and you're out together and she starts dropping hints then escalte.

Anyway hape that helps good luck!!