The squirrels around here are very keen on the bits of peanut, sunflower seeds and hearts in the regular seed mix, but I’ve not noticed them bothering with the smaller seeds or meal worms (they’re mostly herbivores and only eat insects and eggs when really desperate. Ditto acorns). They don’t seem to go for the grated cheese, either, which the robins love. Chopped grapes and sliced raisins/sultanas, though it can take a few days for them to twig it’s food. I’ve seen birds avoid the bird table for days because there was a grape on it.
If the garden’s relatively cat-free you could try chucking some quarters of apple under the bird table for the blackbirds and thrushes (I’ve only seen the blue/coal/great tits eat the apples when the fruit is still on the tree. They seem to lose all interest once it’s fallen. I’ve only seen one occasion of a squirrel eating a piece of fallen apple, and I’ve not noticed them trying the fat balls in the hanger, either, even though they’re easy to reach from the seed platform.