....I'm answering my own post here....

In the past 3 days, I have harrassed every toyota service teck and service manager, AND every toyota "guy" who'll answer the phone....here's what I came up with.

The ideal temps are 185 - 195-degree....But....the stock toyota 3.4L (and probably the 2.2 and 3.0L, as well) will run around 205-210 under normal driving conditions, on a hot day. Which, everyone said isn't great, but as long as you aren't beating on it, and you change the oil regularly isn't too terrible for the motor.

Ofcourse, this is a problem if you wheel your truck....slow speeds....no air being pushed through the radiator...and ofcourse the high loads and RPMS that come with wheeling....all means those temps are going north of 210. Almost all these guys said to go with a 160-degree thermostat if your doing anything more than "normal" driving. One of the service techs did say he's never seen the normal high temps be a big problem. with a yota motor...but that was only 1 out of about 7 guys.

I just installed the 160-degree TRD thermostat in my ShagRunner this evening (little bugger costs $80)....Drove it about 30 miles, doing lots of start/stop around town driving. The highest my temp got was 195 and and it mostly hovered around 185. The 195 was after I warmed it up to 185, then shut it off for 10 minutes. After I started it back up, the temp was 195...but, it dropped to 185 pretty quickly....So, I think I've got my cooling issues solved.

...now I just need a bigger alternator to deal with the draw of that Taurus fan....