I love Montevideo. It’s a smaller, more humble version of Buenos Aires. Bus drivers wave you by rather than speed up to hit you. Stores close on Sundays, and people walk around with giant thermoses and mate gourds to pass the time. We’ve been there twice, and both times we’ve sat back and said, “We could live here; yeah, it would be really nice.” The city borders Rio de la Plata, so it has a serene feel to it.
From Buenos Aires, Buquebus is the easiest way to arrive. You’ll either arrive at Tres Cruces station by bus or at the port by ferry. If you want to go downtown from the bus station, you can either walk (it’s a hefty journey but doable on a nice day), or you can take city bus 188. Exact change is not needed, thank goodness.