I believe the gear ratio is different in the two cars

No, all Ser 2 with the 4T65-E HD, thats 97+ have 2.93 gearing. The 96 SSEi with the 4T60-E HD with 2.97 gearing.

depends on what year you're talking about. Later 97 up gtp'* do have the same engine as the ssei, which I think you are talking about.

i just picked up a 99 gtp over all its a nice car. but in a way i do miss my bonneville. its just not the same ride. but also i went from a n/a to a */c. wowo what a diff.

i would say if you are looking for a cruiser go with the bonne
if your looking for more of a sports car go with the gp

I believe the power end has been discussed well, and to add in my thoughts..

What type of driving do you do?
Bonne is a nice super comfortable car, plenty of room for adults... tons of creature comforts.
GTP is a nice car..harder seats, more sport focused. Less leg room in the back seat.

I personally was pretty unimpressed with the feel of a fully decked out GP GT... though the L67 might help it out some.

Personally having one of each in the stable, I definitely prefer the Bonneville. The GTP seats are not that comfortable except when just running around the block, and the ride is a lot harder. The Bonneville has very comfortable seats, and it rides nice. Although the GTP is the only car I have ever driven other than a Eldorado that I do not have to put the seat all the way back. The GTP is my car of choice for going out, because it feels sportier. I drive the Bonneville 90% of the time because of the comfort factor. Also, I have a 1996 Bonneville model instead of the 2000+ you a refering to.

I sold my 95 SSE some time ago and got the GTP. I will say that the Bonnie is a lot more comfortable. However, I love the GTP. It still is comfortable for long trips, handles very nicely, and still comes with tons of features. I still got to have the HUD like I did in the Bonnie, which was a huge plus. If you are looking to modify the car, the GTP has a larger aftermarket for suspension and cosmetics, and yea, the engine is completely the same.

Arnt most of the suspension kits the same? aside from like the strut tower bar.