Endurance riding is primarily what I do, so the HR monitor has served me well in that respect. Now that I'm significantly healthier and stronger than I was 12 months ago, and also doing regular group and paceline rides, I'd like to start working on other aspects of my riding so I can be more competitive with the faster riders.

TP premium seems to be a good option. I did check out TrainerRoad, per the recommendation of mr_pedro, but my initial takeaway is that TrainerRoad is more geared towards indoor training. Not sure if that's an accurate assessment, but that's how it looked to me. TP does employ a business model that pushes a lot of add-ons in the form of paid training plans and coaching. However, if I'm comfortable building my own plan (which I am, at least initially) it looks like I can do that with TP at no additional cost. Besides, if I do want outside assistance from a coach I have a local resource who is excellent.