We have just come back from that area. Are children are similar ages.
Ment beach itself is gorgeous. We also went to Penbryn beach which ha AMAZING shells to collect at low tide. I am not sure why the shells are so much better there but they are. The car park is a bit of a walk from teh beach so know that you can drop the kids at the beach and drive back-up to park. Poppit sands is great for rock pooling and even in wuite cold weather we found the kids would amuse themselves for hours in wet suits looking for crabs. Poppit is quite exposed though so it is colder.
Just before the Poppit Sands car park is a pub called the Webley. It has a little garden overlooking teh estuary and the we loved taking the kids there for a sunny evening meal.
Our two love castles and Cilgerran castle is stunning. Its very near the Wildlife Centre.
We took a boat trip out from Cardigan. It was with a company called Bay To Remember. The boats are small, low to the water, high speed inflatables. I thought the kids might be scared but they loved it. We say dolphins and seals and it was great, however it also cost a fortune and I later found there were much cheaper (if more sedate) boat trips operating regularly from New Quay.
One coldish day we went to Castlle Henlys Iron Age Settlement. It was a lovely walk and they have rare breed pigs which the girls loves. They also have little iron age houses with story time and activities inside. One even had an open fire. It was a nice way to spend a cold morning.
We like the town of Aberaeron. All the houses are different colours so the kids think its Balamory. There is a lovely gastro pub called the Harbour Master which is worth booking in advance.
If your husband wants activities look at Fforest activities in Cargidan. They probably have a website. They do coasterring and sea kayaking, bush crafts and rock climbing etc. When the kids are older we will def use them.
If you find more good things to do let me know. We have to go every year to see the In Laws and I am always looking for new activities.