Dirt boy is the tuition 3900 for both, or per child, and is it bilingual or just Spanish? Just curious. Our guarderia has been going up 35% a year and is no about 3000 for full day (and I send lunch, the meal service is another 600!!!) I am fed up so I think next year we will be switching to a local (urquiza) bilingual that is currently 3000 a month but includes bilingual and sports at club de amigos, and based on historical pricing they've only been raising 15% a year. But it's a gamble, we might start and they'll say nope we have to raise 40% in March. It's impossible to predict.
For the OP -- Lincoln, Northlands and the one in quilmes (San Andres I think) are all very high scale. But they are also far and with young kids wouldn't consider sending, makes for a very long day as full day is approximately 830-500pm here. No need to add on 45mins travel each direction.
I would rent in Belgrano or Belgrano R where you are about 20mins to Palermo (depends on where in Palermo the company is). In Belgrano and Belgrano R you have a tonne of bilingual private schools. Most of the vacancies at the good schools are gone for next year at this point however, so don't be surprised. However, the IB schools allow foreigners to apply and enter at any point in the year, as do some others. the IB schools Saint Matthews and Islands for instance are very good schools, I've interviewed at both, a warning, schools are very cramped here compared to the USA, the nature of being in a big city. if you want large modern classrooms and huge sports fields you have to go to the burbs, the city schools usually have about 25kids in a teensy classroom we a play area on the roof of the building, and they send them to a club on Fridays for sports.
I just interviewed at St Matthews this year, so I've got the tuition numbers for 2014 -- full day is obligatory from age 5 on. Right now SMC is asking $3900 per month for age 5 and a deposit of 4290. For grades 1,2,3 they are 4700 and a deposit of 5170, but if you send two kids you'll get a 15% discount on the younger one. Grade 4 jumps to $5395 and $5935 deposit. Prices are in PESOS, presume a 30-40% increase for next year considering inflation is hovering around 40% now. Swimming is not included in that price for SMC. Those numbers give an idea as to what the very-good-but-not-absolute-top schools are charging. the lycée francais is supposedly in about 7000 now. Converted to dollars for private education sounds good, but in pesos with 35% increases every year it gets expensive. And the facilities are nothing wow - like I came away from the interviewing thinking, ok that looks like my school -- when I went to my school -- in 1982!!
There is a group on Facebook Buenos Aires Mummy Group, join it when you are ready and they will be able to help with schools.