Between 60 And 65. Its a VACATION. If we are in a hurry, take the car and stay in hotel. Try and live by the 330 rule, 330 miles or stop at 3:30. Did I already say its a VACATION. :)
I'm a low 60's kind of guy. I keep to the right, leave reasonable following distance, and don't drive when very tired. Hard to believe how fast I've gotten old!
Depends on your trailer tires speed rating. Most ST tires are speed rated at 65 MPH. My LT tires are speed rated at 99MPH. So I tow what is reasionable and prudent.