7 days in Laos - more time in Vang Vieng or Luang Prabang?

I'm travelling solo (F 34) in Laos for a week in June and can spend either 3 or 4 nights in either place. Both look gorgeous and I'm struggling to decide where i should spend the extra night.

For reference I'm interested in hiking and outdoor activities, crafts/art/museums/temples. Hoping to keep fairly busy but wanting down/chill time too.

any recs on places to stay too would be amazing - looking at private rooms in hostels/mid range priced spots.

Thank you!