With four people, you'll save a significant amount by flying from the municipal airport rather than the international airport -- roughly half. The cost is around US$50 roundtrip from municipal versus a little under US$100 roundtrip from international. The cab fare between the two airports is US$20 (per taxicab, not per person, and there's no need to tip.)
You can get the exact fare amounts from the Web sites of Maya Island Air and Tropic Air.
Either Banana Beach or Paradise Villas could work for you. Also look at Mayan Princess, Xanadu, The Palms and Villas at Banyan Bay, among others.