1. The boss always listens to Ralph’s suggestions because his ideas are reasonable and down-to-earth.
2. John is just the kind of young man a girl’s parents want her to marry. He’s so practical and down-to-earth about everything.

Synonym: both feet on the ground. Antonym: head in the clouds. The expression suggests one has one’s feet firmly planted on solid ground rather than having unrealistic ideas or flighty behavior.