This is very much a matter of judgement on the part of the border officer. There is no magic number. I have seen (on Border Security) a person with $8 and no bank account allowed in because the people he was staying with assured the officer they would cover all his food and expenses while he stayed with them. I've seen an American coming in near Vancouver headed to Alaska with $1200 denied because he said he needed 10 days to get to Alaska and the officer felt that $120 a day was not enough and he was probably planning to work his way there since he hadn't brought enough money. (She also felt he was planning on spending too long to get there, which made it worse.)
I'm sure you know that $2000 wouldn't support two people in a hotel and eating at restaurants for a month. However if you're staying with friends, then $70 a day for restaurants, travelling around (eg subway fares), and getting into tourist attractions seems reasonable. If I were your border officer (and I'm not, right?) then I'd be fine with the amount of money you're planning to bring.