Practically all dense shrubbery will attract wasps, though that is actually good for the garden if you can keep out of their way. I'll admit that it's a blamed nuisance if you can't, though. I would also plant lots of plants with small flowers (< 5 mm wide), since they attract parasitoid wasps--which don't sting, and will eat the caterpillars that are the stinging wasps' staple diet.

to be honest I cant say that I have noticed lots of wasps near my father in laws conifer hedge.
I don't think conifers would attract them any more than any other hedge type. The benefits of any hedge are better than no hedge.
which conifers are you thinking off? leylandii and the commonest, they need regular trimming to keep them in check. but they do take up a lot of water and nutrients from the soil around them.

Agree. Sorry this isn't an answer to the question but thought yourpartner might like to know there are other options with a similar appearance. Have a look at Lonicera nitida. There is a gold leafed one. When well clipped they make a very dense and attractive hedge that does not dry the ground or take out as much goodness from the soil as conifers do. And they are less prone to wind damage and disease.

I agree with Stera, the lonicera nitida is a great plant. Tiny leaves, easy to trim, can be cut to create 'box balls' or any sort of topiary without waiting as long as box takes and without the box blight menace. The other great thing about it is if you let it get a bit overgrown you can cut it back hard and it will shoot from hardwood, something you have to bear in mind with conifers as many of those won't.
We have robins that nest in our lonicera cut into balls, so much so that it has to get overgrown while they are in residence. It's also dense and protects birds and insects from predation. Can you tell I'm a fan?