I bumped up to 10 GB when they announced the promo because it was during a month I was traveling for work and I was using personal hotspot quite a bit. Even then, my wife and I still only managed to use around 6 GB together.
The next month, I wasn't traveling for work so our usage went back down to what it normally is -- 1 to 2 GB per month.
Based on our usage patterns, there's no reason for us to give Verizon extra money for 10 GB of data when we're just fine with 2 GB.
I wish they'd offer rollover data but it doesn't look like they plan on doing that anytime soon. If they offered rollover data that rolled for 12 months like T-Mo, they'd likely get more money out of me because I'd bump our plan to the next higher tier since anything that was unused would rollover for 12 months and then I'd have a nice cushion for work travel throughout the year when I need it. Oh well...