Follow the coastline northwest and into the Pembrokeshire coast national park. Why not top halfway at the beautiful Musselwick Beach near Dale. Solva is also a great little fishing village and a great place for kids to catch crabs on the quay (top tip bacon is the best bait). St David's is also enroute and you must stop and visit the Cathedral. Then drive on to Porthgain which is one of my favourite places with a stunning pub and fish restaurant right on the front.