Covering a large area along the Yucatán Carib with many different options...Playa Mujeres to the north of Cancun; The Cancun “hotel zone” where grand hotels line the beach, the most touristy area for those who just want to stay on the property; Playa Del Carmen with its many resorts and boutique AI hotels and nightlife off the resort, Akumal for snorkeling with turtles and a quieter vibe, Tulum beach hotels...and the hundreds of oceanfront resorts in between...

How long a stay?
Will you stay on the resort? Or are any more adventurous and want to explore the natural beauty and history?
Is golf important?

I would look at a map and do a little research on the different areas and see if any area matches what you are looking for. There are several resorts that attract young adults, and if you want to enjoy bars or nightclubs off-resort then Cancun or PDC would be worth a look. If Cancun, the calmest water is at the top of the 7, we like the RIU Cancun for example.
3 or 4 star here is hard to advise on, do you have a budget for your accommodations to get more useful feedback?

"Travel changes you. As you move through this life and this world you change things slightly, you leave marks behind, however small. And in return, life — and travel — leaves marks on you.”
-Anthony Bourdain