I think the 90's Bonneville (92-99), especially the 1996-1999 were the best years for this car. Although I have not had the pleasure of driving one yet, I hope to soon as I am considering a 96-99 SSE/SSEi to replace my '91 Cutlass Supreme Coupe.
THE INTERIOR STYLING is my favorite part of this car. I love the way the dash has that aircraft cockpit feel to it, how it slopes down so gracefully from top to bottom. In pictures, this looks completely different. This looks more like a design from 1997 than 1992! And the fact that it can be so sporty AND have all the room and comfort of a Park Avenue is amazing. The 12 way seats, the Red (with green accents) lighting, the electronics, etc make this one cool looking design. Though there are some cheap plastic bits, as with many 80's and 90's GM cars, I think they tend to be well hidden in the styling of this interior.
THE EXTERIOR, escpecially the SSE/SSEi models, have a sporty look to them without being cartoonish (liek the interior) like the 2000-05 models (I'll get to those). The droopy rear end is nicely masked in certain models unlike the 90's taurus, which nothing seems to help. And unlike most people, I think the side vent windows give it a certain "classiness" and I think they really look cool from the inside. The rear window "kickup" also gives it a sporty edge.
I have driven a 1996 98 regency, and a '95 Park Avenue Gran Touring, and I have to say they drove beautifully. They were solid, quiet and smooth, and I'm assuming the Bonneville being on the same platform feels quite similar. The W-Body Cars really seem to trail these cars in terms of build quality.
THE 2000 Bonnneville, I feel was not an improvement at all. The Cartoonish Interior, which was not only smaller, but the materials used were just as cheap looking as the late 90's Grand Prix. The Exterior lost all originality, and It looked more like the Grand Prix on sterioids. The reliability of small but expensive parts (steering shaft, Power window regulators) really turned me away, as did the increased wind noise (Wind Noise is a pet peeve of mine). I don't think the 2000 was bad, but I really think GM could have done better.
Please share your comments, and/or experiences with the 90's Bonnevilles!