I'm for the hex tiles, because as stated in a thread about one unit per tile, it should make blockading a rival civ from acquiring a strategic location for a city, providing you can get enough units to blockade the area before the rival civ gets there.
It always pissed me off in Civ4 how it took so much effort to blockade an enemy area, and so many roads needed to be pillaged to prevent the enemy from reinforcing their city if you perhaps didn't bring enough attackers to take the city in one turn.