I am in the same boat as you and train to trail run/rock climb/mountaineer/ski tour/ice climb locally on the weekends and have been using the ways of Uphill Athlete (awesome custom 8 week plans/phone consultations with coach Seth Keena) to improve my performance.
My biggest learning so far with training is to really know my goal and exactly when I want to be able to perform and focus on one goal at a time. My plan this year is to train to push my climbing grade and do maintenance cardio September to December in order to peak for goal ice climbing objectives in January then switch to training for slogging uphill and do maintenance climbing in order to peak for goal ski mountaineering in May and general mountaineering the summer. The summer is usually too busy with mountaineering trips etc. to follow a plan to improve performance so I focus on maintenance work/enjoying the fruits of my labor.
My main goals are to climb harder ice and be able to handle big vert/mileage for mountaineering days. Turned out that training to push my climbing grade and be an uphill machine is a huge time commitment and very physically demanding work. I gained an appreciation of how much consistent effort it takes to get results and think having a single training focus is best. Knowing when I wanted to be in top notch shape/perform is really key because a fully phased/periodized training cycle is 12 to 16 weeks. Looking back at my first few attempts I was not giving myself enough time to prepare.
Although I have not used the stock plans, I’m sure they follow a periodized approach and each week builds on the previous week as you progress through the different phases so I would go with the plan that fits both the activity you wish to prepare for and time horizon available for training. Repeating shorter plans would be like building a few floors of a building and then tearing it down and starting over instead of building it higher. I would lean towards the longer plans if you can because the sexy specific training that comes at the end is hard stuff and the more time you give yourself to prepare your body the more you will get out of it.
The premium membership for Training Peaks is definitely worth it to be able to make adjustments to your plan because you will likely repeat weeks or need to shuffle workouts. It took a while to figure it all out but all the different reports and the training load scores are really useful for monitoring and planning endurance/aerobic training.