I'd tell you, but I'd have to kill the forum... No but seriously, on a slightly different topic, is anyone else with me when it comes to having just a few spots you kind of like to keep quiet about? For me they're just a handful of restaurants, plazas, recreation areas. Not much, but just a few things I really don't want to publicize. I guess that's that part of me that doesn't care to belong to any club that will have me as a member! (First heard by me from Woody Allen, its usually attributed to Groucho Marx, but appeared originally in Freud's Wit and its relation to the Unconscious) Is that so bad? Anyone with me on that? I kind of feel guilty about it. But for the most part, I like to spread the word. Just like to keep some things sacred :0
But to answer OPs question, Del Plata is great. If you arrive late, you'll miss the backpack crowd and your experience may be a bit more romantic. Although no matter what, its loud there. You should be alright with your price range, especially if you split a big steak. Try the papas rejilla a la provenzal and tell them to make them extra crispy. Yummy. Also, if you're as gauche as I am, go for a malbec rose (with ice cubes in the glass, baby!). Good price and incredibly refreshing in this heat.
And by the way,
Guia Oleo can be a good resource. But its also hit or miss. Some places that are highly rated can be utter crap (the ratings go to the management's head). Stumbled across other places that have atrocious reviews, but are magnificent.
Probably in Lonely Planet by now, but Lo de Paka in Belgrano is pretty good too (kind of a hike from S Telmo ja ja) But you'll get more bang for your buck up here.
buen provecho chicos!!