I don't think the Conrad in PdE is affiliated w/Hilton. Main reason for advice (I gather) to go via GRU is to avoid the current difficulties at BsAs with Aerolineas Argentinas.
MVD has a perfectly serviceable airport--not hugely modern but functional. It is set up in a horseshoe design (arrivals first, then gates, then departures). About a 20 minute drive from downtown.
PdE is about a leisurely 2 hour drive from MVD. It is a toll road, but it is more akin to what we'd call "4-lane divided"--not a superhighway. The last 20 mins of the drive have some beautiful turnoffs to see the ocean.
I cannot fathom how bustling PdE would be during "the season"--I have only heard stories. We were there in September and it was deserted---mile after mile of 12 story apartment bldgs abandoned, shuttered--not a soul around. That, plus it gets dark at 5 pm or so made for a spooky trip. We stayed for $50/night at the Hotel London (?) which had turned the heat off (it was a very cold overnight)--was negotiated by a Spanish speaking co-worker while we were there. Nice breakfast in an atrium in the rain.
We went back on the back roads on Sunday (our business finished on Friday-we were delivered a rental car on Sat. AM arranged by our company). Pretty sleepy places (Saturday would have been more lively) through the Maldonado state. Stopped for a late lunch at a fun local place--primarily parilla but I had pasta, as I recall and my coworker had pizza. Wild to see people going for parilla and literally eating pounds of meat off the grill.
One word--we had a Hyundai Atoz which was fine (smaller than an Accent) for two big guys w/luggage. We used a rental car co. which does lots of work with our company but that didn't have a counter at the airport--a few moments of panic when we couldn't figure out who to give the keys to--they had been told that we'd be there at 5, we showed up at 3, and a few minutes panic before we found someone who called to let them know that we were back.
I'm very fond of the place, as you can tell--just would like to see it in "full on" mode.
jl