What I often hear when encountering friends and service personnel are routine greetings and goodbyes. "Hi" for the greeting, "Have a good one" for the parting.
I also get many "no problem" responses from waitstaff and clerks when I thank them. ("You're welcome" would be better because it doesn't deflect my thanks.) The "no problem" response tends to come more from teens and 20-somethings than older persons.
Consider that you have different options for greetings:
"Hi, how have you been?" or "It's good to see you again, X. How are you?" (Notice that these questions focus on the person you're greeting.) With people who know my Hawaii background, I often say "Aloha," with Hispanic friends, "Hola!" and with Italian friends, "Ciao."
With more literary friends, I sometimes use the question poet Ralph Waldo Emerson asked when greeting friends in Concord: "Since last we met, what has become clear to you?"
When closing, instead of "See ya," try "I hope to see you again soon." If you're with a religious person, you might say "God be with you," the English phrase that is the origin of the modern "goodbye."
Also consider tailoring your parting comments, as in these examples:
To the couple going out to dinner: "Have a delicious evening."
To the business person: "Have a prosperous day."
I think you'll find when you use fresh language that's customized to your audience, they'll feel treated as special, and you might even get "a blizzard of ahhhs" in response.
Until next week,
Loren