Yep sure do, the bigger screen helps when looking at a spreadsheet to see what weights/ sets/ exercises etc are next. Can't say I spend more than 5-10 minutes on the bike, I just use it to warm up.
It's handy to have the iPad for between sets too. I can FB, e mail, or what ever between sets.
I'm not a recreational gym user, I powerlift. So often there's a good 5-8 minute rest interval between heavy sets of squats or deadlifts. Bench pressing is different, it takes so little out of you that you don't need much recovery time.
So for me, the iPad definitely breaks up the monotony on some of my longer workouts (circa 3 1/2 hours), and is convenient for logging workouts etc