Scoping the roof enables you to access 2 helipads as both points of extraction and entry (North and South helipads). Sewers entrance is unique for an Aggressive approach and can't be used as an exit strategy.
These access points are actually not final and there are hidden options, available for each approach. Scope out Casino: reveals 6 access points (Main door, Side doors, Sewers Tunnel, Roof Terrace, Security tunnel, Roof) plus basic points of interest.
