What to do for 3 hours on the trainer?

So Saturday was supposed to be a super fun 60 mile ride in Boulder.  The idea was to get out of the house while my mother-in-law was in town and get some quality riding done in a pretty place.  What actually happened was that a cold front blew in the night before and the Boulder ride didn't happen.  I sent Will and Jan off to the science museum so I could spend 3 quality hours on the trainer.  Ugh.

I really should have ridden 4 hours, but IMO, trainer hours are harder than road hours and its generally ok if you cut them back by 3/4.  Two hours on the trainer is generally ok.  Three hours isn't fun but tolerable.  Four + hours is awful.  So, three hours it was!  Fortunately I had a bazillion episodes of The Secret Circle on DVR and a (now) empty house, so I was good to go.

Here's my workout:
30 min warm up
5 x 1 min speed ups, 1 min recovery
5 (?) 25 minute intervals:
     5 min moderately light gear but >90 rpm
     5 min next gear harder, 80-85 rpm
     5 min same gear, >90 rpm
     5 min, next harder gear, 80-85 rpm
     5 min recovery
5 x 1 min speed ups, 1 min recovery.  Really pushed these speed ups with my harder gear from the long intervals and 95 rpm.  These HURT
spin to recover to finish 3 hrs

I like changing things every few minutes when you have a bazillion minutes on the trainer.  It gives you something to focus on and helps keep you mentally sharp.  This is a hard workout to zone out on because you have cadence targets and changes every 5 minutes.

At two hours, I had definitely hit my trainer tolerance limit and I had to play some mental games to get that last hour done.  But when I was done, my legs felt like they'd done something.  And the next day on my ride, they definitely felt like they'd done something, as my hill climbing was sad and pathetic.