It's personal - why not ride the Bonnie, Scrambler & Thruxton and compare them? Although they're all based on the same package they are very different bikes. I ride a Thruxton, am 51 years old and back to riding a bike after about a 25 year absence. At 1,8m (say 6ft) and 80kg (say 176lbs). I have no problem with the Thruxton's riding position. I need to refuel long before I feel any discomfort and then it's only my knees that need a stretch - refueling allows me to do that. Riding any sports bike requires a reasonable degree of physical fitness, and although you can't compare a Thruxton to a modern sports bike in terms of performance, it does require a similar degree of physical conditioning. Enjoy your Triumph.
BTW My wife and I have owned a Triumph TR6, TR3a and a Spitfire in recent years. My wife loved her fully restored (and modernised Spitfire - brakes, ignition, suspension gearbox and steering) and was gutted when she had to switch to a Honda FRV after the birth of our triplets!