Most hotels will let you you use their beach for the price of a drink, but not all. As someone mentioned, Charela requires that you purchase a voucher - however, guests of the Mirage are welcome to use their beach at no additional cost. I'm not sure what the policy is for some of the more exclusive hotels (i.e. Idle Awhile, Sandy Haven), but I would imagine it is more restrictive to outside guests. Of course, at the big AI's you are not welcome on their beaches unless you purchase a day pass. I have personally hung out on the beach at Kuyaba after purchasing a Red Stripe. The security guard even fetched us a couple lounge chairs and towels, after I tipped him a couple bucks.

As the Captain said, Cosmo's and Boardwalk Village are great places to hang out, with no hassle. They both are sandwiched between AIs, so most higglers don't make their way up there. Cosmo's does have an entrance fee and a charge for renting lounge chairs, but I have heard that they may waive some fees if you eat at their restaurant. The food is good and reasonable priced.

In addition, there are many smaller bars/restaurants that welcome visitors on their beach. Sun Beach and Alfred's are 2 favorites that have great bars and good food. Keep in mind that these places typically don't have security, so you may be on your own when it comes to fending off higglers.