How do your renters access your cottage? Do you mail them keys, or hide them under a flowerpot, in the barbecue or on a hook under the deck? I'm often amazed at the ingenuity of homeowners in finding new places to conceal their keys, but wonder why on earth they don't use a simple lockbox or keyless entry system.
I remember getting a worried call from a renter when he arrived at a cottage because the branch of the tree where the key should have been hanging, had broken off in a storm. There was no key to be found. Fortunately, a neighbor had a spare, but this was sure highlighted the risks of secreting keys around the cottage.
I've always used the Weiser keyless entry systems in our rental cottages. Easy to fit, the Powerbolt system lets you have one code for your own use, and another you can set for guests. We reset our door codes to the last four digits of the renter's phone number, so it's changed for each new group. Home Depot stock these and they occasionally come on sale at around $95.
An alternative is to buy a lockbox, however, I'd suggest you avoid the dial type as they can be challenging for people to use if they are not used to them, or if they arrive in the dark.