I have purchased a Florida vacation home. I have 2 Roku's at my existing house. Can I just unhook one and take it with me and reconnect at my Florida house? Then when I come back home, just bring the Roku with me and reconnect at my existing house?
Yes. Make sure you bring a physical remote if you've been using your phone as a remote. A physical remote is the only way to get it connected to a new Wi-Fi network. If you're using a wired connection then this doesn't apply.
Adding to @renojim 's response...
You'll need to reconfigure for the new network connection when setting up in Florida, and depending on the tv, perhaps a different display type, but that should be all. When you return from Florida you'll need to reset them again.
As long as you don't perform a Factory reset, it will automatically connect to your existing Roku account. (If you should have occasion to do a Factory reset you'll be setting up again from scratch so be sure you link to your existing Roku account.)
If you have any channel subscriptions through your home internet provider, you likely won't be able to access them in Florida, unless you have the same internet provider there. Any subscriptions you have through Roku or services other than your internet provider should be accessible.