The "Other" issues rears its ugly head even moreso on the 128GB. I suddenly developed what appeared like 5-6GB of "Other". It seems like left overs from a failed sync. With no way to find out, I restored the iPad, and I still have a decent chunk of "other". I've read all the Google articles, and no, don't have magazines or comics. I have very few apps that store their own files, like PDF Expert and GoodReader, and it is easy to see what those use under Settings General Usage.
These "is it worth it" threads all end up the same. Worth is relative and it all depends on your usage, your budget, and your tolerance for managing files. Some people use the cloud, some manage their files aggressively, some prefer to store everything locally (like me). I use Music Match to store my 20GB of music in the cloud and have an unlimited data plan, but I still rather keep my 16,000 picture collection with me. That's about 20GB. I have about 40GB of apps, several games at over 1GB each. That leaves me enough space for an entire season of 24, which is not on the cloud because I ripped it from my CDs. The stuff I bought from iTunes is available from the cloud, which is nice, but it is all a push for you to buy stuff from iTunes.
The jump from 64 to 128GB is only $100, and is the cheapest jump. It was worth it.... to ME. YMMV.