On these things I always go from simplest/least expensive to hardest/most expensive.  To that end:

First, are you sure the temp gauge is accurate.  The first thing I do whenever diagnosing anything temperature or pressure related is make sure I have a known good gauge. 

Second, it seems like an airflow issue, but that can be deceiving .  A stuck t-stat can act much the same way.  A water pump issue could also cause this.  If not enough coolant is circulating the airflow can mask that problem. 

Third, given the choice between a flex fan and a clutched an I would chose the clutched fan. 

When was the last time the coolant was changed?  Is it at the correct level?  What about the radiator cap?  Just thinking about all the little things we mostly take for granted in a cooling system.  Sometimes the more we know about this stuff we tend to leapfrog the simple stuff. 

If you want to test the fan clutch let it sit overnight, then spin it by hand the next day.  If it spins more than 5 revolutions you can bet the clutch is bad.  You ca also look at the backside and see if its leaking fluid.  I won't be a lot, but it doesn't take much loss for it to not work right. 

The question that begs to be asked...What was the outside temp?  What is the starting point with ambient temp?  The air around you was totally stagnant.

Sitting in a line with a bunch of other cars to get lunch will always up your water temp.  You are sitting there with other cars belching out heat from radiators and air conditioners.  And your temp in those conditions is not too bad.

No A/C, and it was only in the low 80's outside. I was purposely trying to keep some distance between me and the car in front of me.

Coolant is full, and fairly fresh.

The clutch has noticeable  resistance when cold and if I spin it several time while cold, I eventually can get it to freewheel/spin about 5-6 rotations. Spinning it when hot and I only got 1-11/2 rotations. so that seem about right.

My concern is the fan does not seem to move anymore air cold or hot at idle, based on air flow in front or engine side of the radiator.

The clutch is a Hayden 2710, standard duty thermal. The fan is a 17" 6 blade. I am getting mild seepage around the shaft of the clutch.

I have a 17" 7 blade fixed fan I can try, to see if there is a difference. I really believe its an airflow issue.

I hate to open this can of worms, but it didn't happen with the dual electric Ford Contour fans, those things moved a ton of air. I just like the simplicity of the mechanical set-up and knowing it on. I didn't have a fan controller when I was electric and just ran them all the time because I could never get them to come on at a consistent temp.