The Sessa Marine Key Largo 20 2013 is a deep-V design and the Sessa Marine Key Largo 24 2012 is a modified-V design, so you're likely deciding between two noticeably different on-water experiences. Hull type shapes everything from ride quality and fuel burn to dock handling and resale trajectory.
On paper these two are close siblings in the size department - Sessa Marine Key Largo 20 2013 at 20,0 ft versus Sessa Marine Key Largo 24 2012 at 22,5 ft. Weight tells a clearer story for trailering families: the Sessa Marine Key Largo 24 2012 tips the scales at 3 086 lbs - 1 212 lbs less than the Sessa Marine Key Largo 20 2013 at 1 874 lbs. That difference is meaningful if you're working within a half-ton or three-quarter-ton truck's tow rating, especially once you factor in a motor, gear, and fuel.
The power gap is worth calling out. Rated to 250 hp, the Sessa Marine Key Largo 24 2012 has a 100-hp advantage over the Sessa Marine Key Largo 20 2013's 150-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Sessa Marine Key Largo 24 2012 carries 71 gallons versus 53 gallons in the Sessa Marine Key Largo 20 2013. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.
Both boats are rated for 8 passengers - a good fit for a family of four or five plus guests. Comfort at capacity is another matter; the longer hull typically means more seat options and better weight distribution.
Bottom line: The Sessa Marine Key Largo 24 2012 at 22,5 ft is the right call if deck space, comfort, and entertaining are top of your list. The Sessa Marine Key Largo 20 2013 at 20,0 ft wins on trailering ease, likely lower purchase price, and simpler docking - a solid choice for a buyer who wants more boat for less money.