Side by side:
Slide thickness comparison pic from above:
Grip thickness at the magwell comparison pic:
Notice in the photos above and the measurements below that the P345, while the smallest of the three overall, has the longest sight radius of the three.
Some measurements for you as measured by my Lyman steel calipers:
P345:
Grip thickness (measured at web of hand): 1.046"
Slide thickness (measured at slidestop): 1.151"
Height (measured at tallest point): 5.318"
Trigger reach: 2.838"
Sight radius: 5.870"
P97:
Grip thickness (measured at web of hand): 1.121"
Slide thickness (measured at slidestop): 1.290"
Height (measured at tallest point): 5.434"
Trigger reach: 2.838"
Sight radius: 5.220"
P90:
Grip thickness (measured at web of hand): 1.310" (with hogue rubber wraparounds)
Slide thickness (measured at slidestop): 1.390"
Height (measured at tallest point): 5.434"
Trigger reach: 2.935"
Sight radius: 5.705"