Yes, teach your kids that it's not good to "keep us with the Joneses", but also teach them that feelings of value and approval only come from within. There's a difference between being excited about a trip to Hawaii, and using a trip to Hawaii to show others you have a "good" life. Even little kids can recognize that difference, even if they don't understand the difference.

So yes, do what you can to keep your kids from being jealous brats (lol), but also teach them to see that behavior as a reflection of the person engaging in it and not as a reflection of who they (your kids) are