make a day of (doing something)
To do something for most of or an entire day. There's a fabulous local market in town where you can actually make a day of doing your shopping for the week. If we're going to be at the beach for the volleyball tournament in the morning, we might as well pack our blankets and swim suits and make a day of it.
make a day of doing something
and make a day of itto spend the whole day doing something. We went to the museum to see the new exhibit and then decided to make a day of it. They made a day of cleaning the attic.