Checkin at OMO3 Asakusa by Hoshino Resorts, make sure to book your room months in advance, because this hotel gets full quickly, especially due to the superb views from the rooftop (tokyo skytree and Senso ji temple), and because of the great location.
In the afternoon / evening, you can visit :
Sensō-ji temple, either at sunrise or by night is better to avoid the crowds.
Nakamise-dori Street
Asakusa Culture Tourist Information Center at the 7th floor, for the photo spot
If you have time, head to Tokyo Skytree, but don't go inside, go to Tokyo Solamachi mall instead, go to the 30th floor and enjoy the view of the tower for free!
You can also check Jukken Bridge (photo of skytree) and Takagi Shrine nearby (temple about onigiri).