I've been doing #3. I think it hurts the quality of my above FTP work on the trainer but benefits my overall health. Decided to do this after listening to the Velonews podcasts on the subject.
However, for your specific weakness I might be sure that my long rides included stretches of sweetspot intervals. This makes it hard to do with a group, but I find that most truly accomplished racers train alone, as its very hard to both do your program and ride at a group dynamic. Yes, one group ride or so a week is good to force you to go when you don't necessarily feel like it, but focused training works better solo.
Ok, so maybe a three hours ride with two distinct 20 min sweet spot sessions. I do wonder about increasing my milage overall. I have done 6-7K miles a year for as long as I can remember and my results, give and take, are about the same or maybe getting slightly better (following a plan for a few years and having a power meter for the last two years has made my training more scientific) I do wonder if I was to do 10 or 12K miles a year that would be the boost to my results that I am seeking.