Paint your current return the same as the wall color and you'll notice it far less. I don't personally care for the decorative covers, as a cold air return is perfectly ok as a functional-only element in my opinion.

There are nicer options. hvacpremium.com has a few.

My experience is they also take more time to install, so for a builder to offer these throughout a home is not an acceptable number for a consumer.

On a few home decorating shows I've seen them use these perforated metal sheets as covers. You can paint them the same color as your wall or choose a pretty metal:

Perforated metal sheets