Do you like Punta del Diablo?
 

My sisters and I will be in Buenos Aires for 9 days and are considering a trip to Punta del Diablo. We're looking for a few days on the beach and this was recommended over Punta del Este. Weekend of March 4 - 6. Would love any feedback or tips!

I sometimes daydream about living there in summers, winters here in Buenos Aires.
Imagine Baja, California in the 70's .. hippies, fishing village. I seriously would buy a little cottage or beach shack there ..

Punta del Diablo is very cute. I recommend though you look into accommodation now because that is the weekend of Carnaval, so it could get quite busy. La Paloma & La Pedrera have celebrations over this weekend for Carnaval, but I´m not sure what they do in Punta del Diablo.
Suerte!

I live in Punta del Diablo, and can tell you that although there isn't the same kind of large, organized festival as in Montevideo or La Pedrera the town gets quite busy. Drum troops come out, the clubs open back up and its one of the most pleasant, warm months to spend bathing on this part of the coast. Best of luck, hope you come out!
Un abrazo

Wow, I think our decision has been made based on these responses! Thanks everyone! It looks like there is accommodations available at El Diablo Tranquilo that weekend, so we should probably lock that in.

How would you recommend getting there from BsAs? Ferry to Colonia, then rent a car?

That is what we would do. Ferry to Colonia, rent a car , drive.
You will need a car anyway ..

I will be in Punta del Este on a cruise on March 13th, any recommendations to see or just enjoy the beach?

I would stick to Punta del Este, but I would choose to be independent and not touring in a big bus.
Punta del Este has beautiful beaches, to go around you might think of sharing a taxi, with another couple from the cruise? That has worked very nicely for us in other cruises different destinations. Set a flat fare with the taxi and have a clear idea of what is that you wish to see. Or even better get a guide to come along.
You would have to do some homework, know where you would like to eat, and of course if you enjoy beaches spend some time at the beach. You can have an idea of where to go is you check the itinerary of the tour buses.