I do that too. 🙂
And if at all possible I'll meet them on check-out (maybe even drop them off somewhere) and I will make a point to say what great guests they were.
That's also good to get feedback, both on the things around town they enjoyed, but also if they had any difficulties in our place. Once they've told you something in person there is less need to state it again in the review.
I might even flat-out tell them I'll leave a 5 star review for them, and if I have the feeling that they had a good time generally then I may specifcially ask them to put in a review.
After hearing that, very few people will put anything less than 5 stars.
In general I'm not thrilled with the way the review system works, but you have to make the best of it with the main goal being getting good reviews.