Trawsfynydd if not boiling hot (not a great deal of shade) is top notch. Nothing particularly hard but the rock is quality, landings all good and a lake right there. Also pretty close to you.
Caseg Fraith has lots of options, family friendly parking and approach, with the option of Idwal Cottage a bit further down the road too.
RAC is the popular choice but can get super busy and the rock is pretty shiny. Fighting off random dogs from your sandwiches can be half the battle.
Some seaside venues have bits and bobs of easy bouldering on Anglesey. Moelfre, Benllech has some random stuff on the beach for barefoot shenanigans, but being on the beach and eating icecream will be the priority over good bouldering. Trearddur Bay on Anglesey has a lovely little crag (tidal) called the Ghost Cave which can be gloriously warm and plenty of rockpooling options.