I drove myself crazy doing research on the best options! Just search "smart locks" on this forum and there are some great threads with lots of information. The top names that kept coming up were August Locks, Yale, and Schlage.
The August locks were tempting because they looked super easy to install (no need to replace your existing deadlock/key) and you can track entry/exits but I wanted a keypad and that was separate and seemed kind of cheap looking. Plus, the reviews were mixed. It seemed to work well for some, not so well for others.
I finally went with Schlage BE468CAM619 Connect Touchscreen Deadbolt. It works fine on it's own (up to 19 codes that can be deleted after guest checks out), and if I want to manage codes/locking/tracking remotely I can hook it up to a Wink hub or Smartthings or some other compatible system in the future. I rent a room in my home so being able to manage remotely wasn't really a big deal but I do like the idea of monitoring locks and unlocks to verify when guests check-in or out.
The lock was only $160 on Amazon so I consider it a great purchase!