I know on some vehicles, and can do something to temporarily shut off the headlights.
(On my 99 Blazer, you had to hit the dome light switch 5 times).

Is there anything like this on the 2000 Bonneville models?

You would have to do a DRL rewire and put a button in the cabin as a on-off switch to turn them off.

I'd check the owners manual. I also have a truck and appreciated the ability to turn them off at times.

I haven't found a way to do it on the Bonneville. You can turn off the headlights and leave on only the parking lights by turning the headlight **** from "off" to parking. the parking lights will still be on though.

Thank god my car has Off, parking, headlamps, AND auto on it... It'd drive me nuts not being able to turn my headlights off when needed.

if you have your car in park, you can turn all of your lights off but switching the **** on then off. I dont have a pic of it. but its the **** next to the one for your interior lighting..
the **** for the timing of how long your lights stay on after the car is turned off. other than that, no rewire is the only way

*edit* this is what I am referring to..

Hehe, it was a good question.....

Sometimes I like to sit in the parking lot and listen to my radio for a while with the car running some evenings. I don't want the headlights on then.

While driving, when I turn my headlight switch on parking, the parking lights come on and the DRLs also remain on. The only way to turn off the DRLs while driving (without rewiring) is to turn the headlights on in my car.

Turn everything to off. Should work, I believe it works on my SLE.

Temp shut them off...Yes in drive at night, you need to switch to park, that'll turn'em off. But in the day, there isnt a way to turn off your DRLs unless its rewired.