Playa de las Américas is Tenerife's loud, purpose-built south-coast resort: sunny, convenient, heavily developed, and not even slightly shy about what it is. If you want whitewashed villages and silence, look elsewhere. If you want beaches, bars, late nights, and easy access to excursions without renting a car, it does the job very efficiently.
The resort runs into Los Cristianos on one side and Costa Adeje on the other, creating one long strip of hotels, restaurants, shopping centres, and seafront promenade. The best local swims are at Playa de Troya and Playa del Camisón, while Siam Park is close enough to dominate many family itineraries.
The bargain with Las Américas is simple: little local charm, huge practical convenience. Ferries to La Gomera leave from nearby Los Cristianos, buses run along the coast, and the south airport is close. Use it as a sunny base, and save your expectations of old Tenerife for La Laguna, the north coast, or the Teide highlands.