I base my winter training on my goals for next season.

1. My 2015 season starts in March/April with short crits and club-races. [PEAK]
   These are short high-intensity races that really demand treshold and VO2 efforts.
2. During the summer I will participate in more endurance-type rides of over 2 hours and such. [BUILD]
3. At the end of the summer there will be some European Cyclo-Sportives (road races that look a little like the European Classics). [PEAK]

That means that my training should focus on:

1. Building Tempo, Treshold and VO2Max over the winter
2. Build Endurance over the spring and summer
3. Build Endurance, Tempo and Treshold towards the end of the summer.

This is convenient for me, because work and climate in the Netherlands doesn't allow me to do long rides in the winter. I can, however, get in 2 or 3 rides on the trainer and maybe one outdoor-ride in the weekend. This is fine because on the trainer I can do 90min sessions focussed on treshold and the like (I like Sufferfest films for this).
I also do strength training in the gym 2 or 3 times a week to increase power. And play soccer twice a week which is also interval stuff.

When the spring comes around I can do more longer rides outside and start putting the longer Z2, Endurance rides. There are many (non-competetive) organized tours around here in that period that are 120-150 km long that are perfect for building some endurance base for the late summer peak.

At the end of the summer there are a few (hilly) cyclo-sportives that I want to do. These are aprox. 130km and can be considered road races. They require a very good endurance base but also tempo and treshold work. That is the focuss of summer training.

Also at the end of summer/begin fall, there will be some crits again which I will just do for fun without specific trianing.