You're not far from where I'm from!
Penbryn, Tresaith, Mwnt, Aberporth are all great beaches, Llangrannog too. The biggest one's Penbryn if you're worried about crowds but there's more stuff like pubs, cafes etc around Aberporth, Tresaith and Penbryn. The coastal path around that entire stretch is amazing. New Quay's a great seaside town, it'll be busy there though.
You're only about an hour away from Oakwood theme park. Again not sure what the situation is with Covid but it's a great family day out if it's open.
Make sure you get some honey ice cream if you're in Aberaeron, it's delish.