As far as workouts go, you can't beat sprint intervals. Yeah, they suck, but they build endurance, build your leg speed and are great cardio. Hill repeats are also good way to build your endurance, and build your leg strength. My typical workout usually varied between sets of sprints and hill repeats alternated with longer endurance rides, which can also be taken as recovery. A longer ride, 20 miles or so, with light resistance on flats is a great recovery day ride.
A lot of people aren't fans, but I believe that indoor cycling on a spinning bike, it's some of the best preseason training you can do. I've never been a fan of trainers or rollers, although I've used both. If you do take a spinning class, make sure you've got a bike with clip pedals and a heavy flywheel. The old Johnny G spinners are the best. You can buy one pretty cheap too. They make for great trainers in the garage on rainy or cold days. I also suggest NOT taking an aerobic cycling class. It'll just frustrate you. if you work at cycling program with the trainer, incorporate your sprints and high resistance hill climbs. After doing an off season of them in the garage, you'll be amazed at how much faster you are on the road.