Q: why would i want 128 gb iPad vs 64

The only advantage to the 128 over the 64 is more space. If you don't need that much space, no advantage. However, 5000 photos could take up a lot of room. You'll want to check on how much space they're using before deciding.

The links below dont address 64GB vs 128GB, but the info can provide some guidance. Unless you store a lot of videos/movies, you probably non't need128gGB. Hpwever, whatever size you get, it cant be changed.

16GB vs 32GB vs 64GB: Which new iPad storage capacity should you get?

http://www.imore.com/2012/03/08/16gb-32gb-64gb-ipad-capacity/

How much content will fit on my iPod or iPhone?

http://support.apple.com/kb/HT1867

How Much iPad Memory Do You Need?

http://ipad.about.com/od/iPad-Tutorials/a/How-Much-iPad-Memory-Do-You-Need.htm

 Cheers, Tom