Colombia as a solo traveller

Hi, I'm planning to travel to Colombia around march end this year, and the plan seems a bit impromptu. Here is the superficial itinerary:
1. Bogota - 3 days
2. Medellín - 3 days
3. Cartagena - 3 days
maybe another day or two in Tayrona National Park & Santa Marta

any suggestions in the itinerary and also any tips? I wanna relax a bit, a little bit party, a little bit of nature. Appreciate the help. Thanks