Paraguay has so much to see and do that 1 week is not enough if you really want to get into the wilderness. That said, below is a 1-week itinerary designed as if treating Paraguay as a stepping stone between Argentina and Brazil. A second week gives you the opportunity to dwell a little longer and enjoy the Jesuit ruins of Encarnación and the country's untouched natural parks.
Days 1-3: Asunción & Environs
On your first day, fly into Paraguay's riverside capital, stay in the central Crowne Plaza, and explore the city by foot and taxi, seeing firsthand the strong tribal heritage in the city's museums. Day 2 can be enjoyed in the leafy upscale suburb of Villa Mora and the nearby Jardín Botánico. On your third day, take the rural tour called "Circuito de Oro" to visit the charming Iglesia San Buenaventura and the resort town of San Bernardino on Lago Ypacaraí or, if you have jungle fever, visit the pristine rainforest at Parque Nacional Ybycui.
Day 4: Ciudad del Este
You might hate it, but you'll certainly enjoy telling the folks back home of your time in this "Supermarket of South America." Revel in the gritty commercialism of the world's third-biggest tax-free zone by visiting its tacky stores and slick shopping malls. Spend the night in tropical splendor at the gorgeous Las Ventanas hotel.
Days 5-7: Itaipú & the Border, then back to Asunción
On your last days in Paraguay, explore its less consumerist side. Start by visiting the engineering blockbuster that is Itaipú and the spectacular Salto Monday falls. The next day, cross the massive Friendship Bridge and see the famous Iguazú Falls in Brazil and Argentina. Cross back over to Paraguay and spend your last night in the capital at the well-appointed Sheraton Asunción.