Suggestions for where to place the key

This weekend, I sat my wife down and shared with her my dream of chastity (yes, you can see it in my username). She didn’t know a thing about what it was at first, but as soon as she realized she’d be the one making all the big decisions about what happens to my cock, she got really interested. She wants to show off the key in a way that feels both feminine and sexy. Her default plan is to wear it on a long necklace that rests inside her bra, though she’s open to other creative options too.

Got any suggestions?