I liked the old keys that were actually keys on a chain like dog tags. Had the room number on it so people could find your room if you were a little out of it.
That's very thoughtful of you. I just carry our tip money and key tucked in my square cuts. The bartenders are used to getting soggy tips from me. But they get enough that they really don't mind.
Vacation Vault. We've been using this for years on all of our vacations, and it works great. I wouldn't leave passports or the Mona Lisa in it, but it provides enough of a deterrent to protect your key and some cash. It's big enough to hold phones and cameras as well. Amazon.com - Vacation Vault Yellow Portable Protective Combination Lock Box - Lockable Storage Box
I've been known to stick a card key in the front of my panties before for nights at Paty Os. Keepin it Klassy, lol!