I've planted both sunflower and zinnia by broadcasting them, but I never
planted them together. I'd expect that it would work though.

Basically just toss the seed loose on the soil, gently rake it in and
water. The seed should be covered by between 1/4 and 1/2 inch no more.
Do not "bury" the seed. It may be a little early to start these seeds
outdoors. Check the sowing dates in your area.

Rake easy and don't pull your back out.

To say I'm planting them for my benefit, I would only mean it in the
sense of using some for cut flower arrangements (not like at a
farmer's market), or just for the view. Mainly for the view and for
wildlife. I have never used any kind of pesticide in my gardens.

The two areas combined are probably around 5,000 square feet. Are you
suggesting that broadcasting the seeds is a better method for weed
control than rows?

Thanks!