I'm right there with you. There is always the "Do you really need this" devil in the back of my head. I'm usually at 32gb but now I'm considering the 64gb, but I'm waiting on upgrading my ipad mini.
HOWEVER,
Sometimes, having a little hard drive disclipline goes a long way. I'm sure there are a whole bunch of things already on your other ipad that you haven't accessed in months...maybe even years. Just carry overs from your restore upgrades. I'm a DJ/producer so I have a Macbook pro with 750gb HD, but if I really look at my drive, I'm probably only using 300gb. The other 200 gb being used is just crap I'm too lazy to look through. I have a Macbook Air I use all the time and it's 120gb. I was worried when I bought it but I have been really disciplined. I still have 50gb left and I feel I have almost everything I need, aside from music.
I probably just made it worse. lol