Looking for full size SUV for family car and towing larger -35ft RV’s. Buying used, 3-7 years old. I like the armada platinum interior better but what model/year would you recommend for longevity? Or maybe another full size 3rd row option? Thanks and keep it up!!

Definitely get the Sequoia over the Armada.
The Sequoia is better for longevity than the Armada. Realize the Sequioas only two 7,000 to 7,400 pounds. If you are towing more than the Sequioas are rated for, find the Excursions with 7.3 L V8 diesel engine. They tow a lot of pounds more than the Sequioas while carrying your family around and decent reliability.
Sequoia. No question. Especially for longevity.
Go for the Sequoia, esp. if you plan to keep the vehicle for a long time.
We have some Armadas in our neighborhood and they look big and impressive going down the street. I'll stick with Toyota. Every time I see an Armada I think of the Spanish Armada that was destroyed by a storm in 1588. Bad vibes.