Of the supercharged cars, here'* what I have found.
Park Ave: The largest and most luxuriest. The softest ride, cushiest interior and toughest to make it handle better. Engine/trans mods are plentiful for 97+.
Bonneville: Little cousin to the PA, it is the true Luxury with Attitude like the commercial said. Powerful, roomy and some handling mods available. No heated seats until 2000. Engine/trans mods are plentiful for 97+.
Regal: Reminds me of a shorter wheel based Bonneville, yet it was redone for the 97 year. A little lower to the ground than a Bonne. The Regal gives a better turning radius and better electronics that the Bonneville didn't have until 2000. Available with dual heated seats and a ton of suspension mods. Basically anything that works on a GP will work on the Regal. Engine/trans mods are plentiful for 97+.
Grand Prix: Like the Regal this is a W body and was redesigned in 97 with the 3800. Being performance based this car is low to the ground and rides like a sports car. Seats are firm and not comfy for long trips. GP owners suffered a bit as GM gave them the option of only one heated seat. Girlfriends and wives around the world were shunned. Tons of suspension and handling mods available as well as engine and trans mods.
Monte Carlo/Lumina: Oddly both are W bodies and got the 3800 NA motor in 98 only, then the 3800 came back into the Monte around 2004, along with the SC 3800 being available. Being a W body, everything is available for suspension and engine like the GP/Regal. Heated seats unknown.
What can I say..heated seats rock.
00 Regal GS: All kinds of cool stuff.