Oh, I'm so glad you are traveling to Rovaniemi, my old hometown! I have a few tips for you what to do here and where to stay. Feel free to combine these activities, leave something that doesn't feel suitable for you or go even twice somewhere! There is a public transport in Rovaniemi but if you want to feel completely free and take advantage for sunrises and sunsets, renting a car is something I would suggest. Eventually all of these places are not too far from each other, maximum 30 minutes drive from Rovaniemi city.
Welcome to the most lovely city in Lapland! I hope you enjoy your stay!