I'm for telling her straight out. Like everyone else has said, though, there's no need to tell her everything. You don't want to pressure her too much or scare her away before she's really had a chance to explore your interests and think about them. I think it works best if you start out with a few of the lightest activities you are interested in, and if she's game for that introduce more. If she says "oh, that's too much" be completely light hearted about it and assure her it's fine. Don't tell her like it's your deep dark secret. Tell her like it's something fun and interesting that you can explore together.

If you are lucky, she may have an undeveloped or secret dominate side, and you may have a wonderful D/s relationship.

If you have average luck, she may be willing to do some of the things you are intersted in, and you will have a satisfying sex life with your mostly vanilla partner.

If you are unlucky she will run for the hills, and then you don't want her anyway.

This is based on my vanilla dating experience, and the experience of a male sub I know who doesn't have a partner.