Veteran key forward Staunton sparked the Giants with the opening goal of the match but it was their sharp ball movement that proved the difference early in their 7.2 (44) to 4.8 (32) triumph on Sunday.
The Giants' (4-6) focus on slicker transitions clicked in the final round as they kicked five first half goals, but they still had to hold off a late surge from the Suns at Sydney's Henson Park.
Staunton kicked a trademark major after receiving a handpass out of a pack and quickly sending a long bomb from inside the centre square bouncing through for the first goal of the game.
But it was livewire forward Georgia Garnett who lit up the Giants from there with three goals from 14 disposals to put a stamp on an outstanding second half of the season.
Key defender Hetherington finished with six disposals but failed to kick a goal despite being a clear target for her teammates late in the game.
The Giants allowed the Suns' talls Lauren Bella (33 hit-outs) and Jac Dupuy (16) to control the ruck, but the hosts' on-ball brigade led by Alyce Parker (24 disposals) matched them at the stoppages.
Ally Dallaway (16 touches), Tarni Evans (17) and skipper Alicia Eva (13) also stepped up for the Giants when the game was on the line early.
"It has been an up and down season but we've always just talked about getting better, and growth, and we've finished off the second half of the year 3-2," Giants coach Cam Bernasconi said.
"Tanya made the decision to retire during the week. She is a fantastic person, not just a great servant as a player."
The Suns (5-5) started strongly despite the disappointment of missing out on a top-eight finish when the Western Bulldogs secured their finals spot earlier in the round.
The two teams went goal-for-goal in the first term but the Suns were unable to keep pace with the Giants until kicking the last two goals to get within 13 points with five minutes to play.
Charlie Rowbottom and Alison Drennan (both 27 disposals) finished their own impressive seasons on a high, while Claudia Whitfort (18) also battled hard and Ashanti Bush kicked two goals for the Suns.
"It certainly wasn't the way we'd like to have finished off our season, being our best season so far," Suns coach Cameron Joyce said.
"The first half was the difference really, the Giants were just a bit cleaner and took their opportunities in front of goal, kicked straight and put us on the back foot."
The Suns end the season with the most wins in their AFLW history but will rue losses such as this as they reflect on their ninth-place finish.
