I've never been on a 'family' plan but apparently you can get pretty good deals that way. Good for you! (no sarcasm, I mean it). But for the average 'single' customer the difference is quite big. $100/month (average) for one of the 'big 4' providers = $1200/year. Straight Talk at $45/month =$540/year. Difference of about $660, which can be used to buy a new phone. I myself bought a mint iphone off craigslist for $300, and my savings over the year are even better. And when you factor in the SECOND year as you did in your comparison, the savings are about $1220. So you could get a brand new phone EVERY YEAR on straight talk (as opposed to every 2) and still not lose any money compared to AT&T. PLUS on top of that you aren't locked into a ridiculous 2 year contract.
On a side rant - the whole 2 year contract thing has to change soon...I think it already has started to considering the recent big push to prepaid coverage. A couple years ago it was ghetto to do prepaid, but now a ton of people (myself included) are doing it. I mean - who is really going to keep the same 'smartphone' for 2 years these days??
EDIT: Oh yeah - what's with the $25 data? You're telling me that your whole family of 5 only pays $25 for data every month? No offense but I don't buy that. What, do you guys get like 10MB each?
Oh lol - and one more EDIT: after reading your post again - you realize that the 'family plan' you are getting actually comes out the same as straight talk? The only benefit is the subsidized phones, which is legit, no doubt. But that just tells you how great Straight Talk is: it offers family-plan rates to individuals. Can't argue against that