Just download less :/ use free open wifi more. I am sorry but some people must really abuse their downloads to go over some caps.
Free and open Wifi Hotspots are not that common, yes Coffee Shops and such have them, but many hotels charge and you can't listen to streaming radio while driving down the road using hotspots.
Honestly, it doesn't take much to get into a higher data usage, I manage the cell phones for our office and most people are in the 2-3 GB/mo. range (They are not tethering by the way) and some get into the 3-6 GB/mo. range. This is only going to increase with iCloud and such bandwidth hogs.
Many ask how you reach that, well, what they do is all Apps are downloaded on the phone, as well as songs from iTunes, add to that Books (mostly Kindle), then add in Netflix, toss in some Youtube and streaming audio and you have the answer as to how this is possible.
Now, to be honest, unlimited data should indeed mean unlimited (without restrictions, aside from those saying not to commit crimes of course), not throttled or restricted from being able to tether.
As far as tethering, my wife and I have three lines that we tether from, one AT&T and two T-Mobile, one of the T-Mobile lines is a mobile hotspot, the other is an Android phone, they both have data throttling, so we split our usage among them and find that we rarely, if ever go over the limits to be throttled. But it works out a lot cheaper than getting home internet in our area:
Cable - $60 per month
DSL - $30 per month + $40 per month for the phone line (cheapest phone line available from the phone company in our area and bare DSL doesn't seem to actually work here)
Both options have a 5 GB/month data cap, if you go over, your service is cut off for the rest of the month with one and I think you are charged extra for the other now, I can't remember which is which though.
T-Mobile Hotspot - $30 (after discounts, but it is throttled after 5GB/month, but since we have two other lines that have unlimited data, it is not an issue anyway)
The problem boils down to AT&T not being willing to upgrade their network and that we live in one little corner of our city that gets neglected by everyone, since if we cross either the streets (we live on a corner) we are in another town.
As for the 5GB limit on the AT&T data plans, they never put that in the business contracts, so they are not covered for us.