My 2001 now has about 137000 miles on it. The transmission is starting to take some time to engage after sitting in the garage overnight. When you first start it and put it in reverse, it takes about 3 seconds or so before it actually engages reverse. Fluid condition looks very clean. I've been wondering if the transmission is getting ready for a complete failure? After the first engagement, all is well and drives completely normal. Only after sitting for some time (8-12 hours) does the transmission do this.

What does the board here think and recommend?

Change your fluid and filter. https://www.gmforum.com/t278423/ Make sure you get the correct GM transmission fluid. You will need about 7 quarts, a filter, and a pan gasket. The only special tool you will need is a inch pound torque wrench to torque the pan bolts to 120 inch pounds. I suggest the clicker style. I have used both a clicker and a dial type. The clicker is way better. Follow the instructions I have laid out in the write up and you will be fine. Takes about a hour and a half or so. I would guess the filter is getting plugged preventing the pressure from building up to shift.

Thanks for the quick reply. I appreciate it. I had read a fair amount of negative comments about the trannies in these cars and just wanted to hear from those who have some real world experience. The Bonnie has been a pretty good car, and the tranny has always shifted very well. I had already planned to do a filter and oil change, but was curious if the symptoms I have are indicitive of a soon approaching complete failure. I've done a fair amount of shift kits in a variety of other automatic transmissions, so I'm no novice to a simple filter and oil change. Hopefully you are correct and the maintenance will help this one last another 50K miles or so before I retire it as my wifes daily driver.

In the how to area I also have a write up about installing a shift kit in your trans. It has the lengths for the spacers listed.