I'd agree that they can be pretty boring. I really focus my workouts when I'm using mine in the winter. Hard workouts are typically some type of interval set which takes about 1.5 hours. On days I would do a long ride and I'm stuck inside I get up early and do a 2 hour block then come back in the afternoon for the other 2 hour block.
To combat the boring factor I use podcasts, audiobooks, and movies. I also hide the clocks and set a timer where I can't see it so when it goes off I'm done. I've found not having the time visible makes it pass faster (watched pot never boils).
I don't purchase new tires but just use the old one from the summer then get a new set for the following season. If I had a spare wheel then I'd use a training tire but it's just too much of a pain to switch rubber when it's nice enough to ride (which happens once a week at least for me).