1. Beaches to spend an entire day- Morjim (NorthGoa) https://www.tripoto.com/trip/a-day-at-morjim-beach-5e09fc1601f33 , Palolem.
You can just lie and enjoy the beach and get tanned. You'll find everything you want to eat and drink and smoke at the beach.
Arambol beach in North Goa is full of hippie vibes.
2. For Sunsets- Benaulim beach https://www.tripoto.com/trip/goa-for-peace-seekers-5e088518e6a67 , Vagator, Chapora fort.
3. Clubs- LPK, Mambos.
If you want an experience of a chilled out pub then you MUST visit Soro- the village pub in Siolim- North Goa
4. Places of Architectural interest- Old Goa Church, Aguada fort, Chapora fort, Sinquerim fort.
5. You must try out hostel stays in goa if you're traveling solo.
6. If you want to just sit and have few drinks with loved one then theres a place called Mango tree in Vagator. Its a chilled out place and there's no chance you won't enjoy it. The ambience over here is too good