An access device for performing a medical procedure using a trans-septal approach, comprising: a dilator comprising a proximal end, a distal end sized for introduction into a patient's body and terminating in a distal tip having a tapered shape, and a lumen extending between the dilator proximal and distal ends; and a needle device (40, 140, 240) comprising a proximal end, a distal end sized for introduction into the dilator lumen and terminating in a sharpened distal tip, the needle movable relative to the dilator to selectively expose the needle device distal tip distally from the dilator lumen and advance the dilator relative to the needle device, the access device characterized in that: the dilator distal tip comprises a distal-most region (65A-1) having a first linear taper defining a first angle relative to a longitudinal axis of the dilator, and a second region (65A-2) adjacent the distal-most region (65A-1) having a second linear taper defining a second angle relative to the longitudinal axis, the second angle being smaller than the first angle, wherein the distal-most region (65A-1) is formed without any external coating, and the second region (65A-2) is formed with an external coating; and the distal-most region has a first length and transitions from a first diameter to an intermediate diameter, and the second region has a second length and transitions from the intermediate diameter to an outer diameter of the dilator, wherein the regions are configured such that (D2-D1)/L1 is greater than (D3-D2)/L2. a dilator comprising a proximal end, a distal end sized for introduction into a patient's body and terminating in a distal tip having a tapered shape, and a lumen extending between the dilator proximal and distal ends; and a needle device (40, 140, 240) comprising a proximal end, a distal end sized for introduction into the dilator lumen and terminating in a sharpened distal tip, the needle movable relative to the dilator to selectively expose the needle device distal tip distally from the dilator lumen and advance the dilator relative to the needle device, the access device characterized in that: the dilator distal tip comprises a distal-most region (65A-1) having a first linear taper defining a first angle relative to a longitudinal axis of the dilator, and a second region (65A-2) adjacent the distal-most region (65A-1) having a second linear taper defining a second angle relative to the longitudinal axis, the second angle being smaller than the first angle, wherein the distal-most region (65A-1) is formed without any external coating, and the second region (65A-2) is formed with an external coating; and the distal-most region has a first length and transitions from a first diameter to an intermediate diameter, and the second region has a second length and transitions from the intermediate diameter to an outer diameter of the dilator, wherein the regions are configured such that (D2-D1)/L1 is greater than (D3-D2)/L2. the dilator distal tip comprises a distal-most region (65A-1) having a first linear taper defining a first angle relative to a longitudinal axis of the dilator, and a second region (65A-2) adjacent the distal-most region (65A-1) having a second linear taper defining a second angle relative to the longitudinal axis, the second angle being smaller than the first angle, wherein the distal-most region (65A-1) is formed without any external coating, and the second region (65A-2) is formed with an external coating; and the distal-most region has a first length and transitions from a first diameter to an intermediate diameter, and the second region has a second length and transitions from the intermediate diameter to an outer diameter of the dilator, wherein the regions are configured such that (D2-D1)/L1 is greater than (D3-D2)/L2.