I'll second that it sounds as if you're wanting to swing or simply have an open marriage. We have some folks here who also swing and do open--those aren't the focus of this site, though. You may find discussion more to your liking on a swinging site.
As for asking her about what you want to do, I'm generally a fan of simply asking for what you want. "I'm interested in X--what do you think about it?"
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.