Last minute S. America Trip suggestions?

Based in West Coast USA. Last week of May. I was thinking Quito, Ecuador to just chill and relax in the city, maybe a day trip out of town. Peru would be cool but I know peak season and Machu Pichu tickets are difficult to come by. I've also wanted to visit Buenos Aires and Montevideo. I had to cancel plans to visit Mexico and have wanted to visit numerous S. American locations. While I am kind of active and outdoorsy, I am leaning towards a more urban city/ chill and eat/ drink holiday while recharging my battery. I am trying to be somewhat budget savvy.