Thank you all. The radiator was filled with fresh fluids two years ago when the timing belt and water pump were replaced. It looked pristine. I will replace the coolant, thermostat and cap and then I will take it from there. I will let you all know how I make out. I do hope the head gasket did not go. The temp gauge never went beyond the 3/4 mark even when it boiled over. When the car sat or I drove in traffic the gauge stayed at the middle mark. It only moved up when I accelerated. I will update you next week when I complete the repairs. I am going to Texas tomorrow and would not be back till Monday. The parts come in on Tuesday.

 

Don't guess on something so critical to the performance of your car.
Get a pressure test done and make sure you don't have any hidden problems. You can't see everywhere the coolant goes and have no ideal what might be going on in there.
Find out what's broken and fix it...

 

I replaced the thermostat and the car is running like a top. Thank you everyone for your contributions.

 

This scenario seems to lend itself to add thermostat replacement as a 90k service with coolant service. Since some coolant will be lost with a thermostat replacement the combination of coolant service and thermostat replacement seems like a no brainer to me. Interestingly, despite the ease, I found that most dealers don't include it in their 90k package.

 

I think the concern you're hearing here is that radiators don't boil over unless something else is wrong. This is a symptom, not the problem. Yes, it could be as simple as a cap plus a new thermostat but at 200 Grand you need a careful checkout of the cooling system.
The absolute fastest way to completely junk the car is let the motor overheat. Since it's primarily aluminum, it can overheat quickly and then distort and warp. Can't be rebuilt - only replaced. Reference the costs quoted above - good numbers and close to or above your current value.