The only problems we had with this car were with the brake pads, once we had those replaced, we haven't had any troubles. Even after the 100k mark, the car still has a lot of power and is a joy to drive. If you are planning on buying a monte carlo, I can't say enough good things about the vehicle. Of course, the car we now own is of an older body style. In 2000 Chevy came out with the newest look, so I can't comment to much about these later models. Enjoy the ride!
There is plenty of leg room, even for a six foot, 270 lb man such as my self. The motor driven drivers seat is a nice feature, especially since my wife and I both drove the car. If you do a lot of traveling to see the in-laws like we did, there is plenty of space in the trunk.
I can't think of any improvements that I would make to this vehicle. It has been a joy to own. Good luck on your purchases.