I got GTA IV on the day of its release--I still remember that day, but that's a story for another time. Anyways, Liberty City, although not as big as San Andreas or the frontier in RDR, was still huge, I think. So huge, in fact, that two years after I got GTA IV, I drove down a street that I had never driven down before. Since then, I haven't found another street that I have not traveled down.
What about you guys? Have you explored Liberty City to its max? How long did it take you?