There is nothing too startling here but enough for a quick session while the kids play in the sand. It's all very obvious.
One problem at Criccieth is that people tend to set up their beach camps right where you'll want to boulder. An evening visit might be better here.
Borth y Gest has some bouldering too. Mostly a long traverse and one steep section where Huffy did a hard problem.
There are brief details on page 252 of the NWB guide, but the quotes from the Trem guide are spot on (of course, because i wrote them
)
If it's raining you could always nip off for a session at Hylldrem which is not too far away. There are also some good easy problems round the back of the upper tier of Pant Ifan.