I've only seen the Lines from the ground, from the rickety lookout tower beside the Panamerican highway. They're interesting enough, but I'm not sure they're worth an entire day from Lima. You'll get about 15 minutes max I'm guessing, to see the Lines but you'll be on the road from dawn until dusk. That's going to be a three hour trip one way between Lima and Paracas, maybe more if there's traffic (which there almost certainly will be).

Also, the Maria Reich Museum in Nazca was worth seeing, and going by air you'll miss that.

All that said, I think the Nazca Lines are interesting and if you only have a day to see them, then the alternative you're choosing is the best one.

If you're doing this between mid-December and March, get the driver to stop in Asia, about 100km south of Lima. It's an upscale beach community where many rich Limeņos have their summer beach homes. There's a commercial center right beside the Panamerican Highway where many of Lima's most popular restaurants (Antica Pizzeria, Segundo Muelle, etc.) have set up shop. There's also a Wong grocery store. Nice place to take a break on the long drive back to Lima.