Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
I don't know if it's worth the extra cost to go for the triple a/b/g option. I use Intel's b/g option and it works just fine at all the hotspots that offer wireless.
As for the quality of connection, it depends on the hotspot itself. I get excellent signal quality at Diedrich's coffee, most Boba cafes, and some stores like 99 Cents Store. I haven't tried wireless at Starbucks b/c they charge for wireless unlike Diedrich's.
You really only need 802.11b/g - I don't think any hotspot uses 802.11a.
I haven't used Starbucks or Barnes & Noble, but I do use the local coffee shop setup - they charge, but it's reasonable, especially if you pay for a year upfront. The university has an open WiFi network - and it's pretty fast. You can just go to campus and use it, you don't have to be a student.
One thing to keep in mind is that public hotspots may block certain ports, so if you're looking to use certain programs (i.e., BitTorrent, P2P, even some FTP apps), they might not work on that network. But that's going to be a case-by-case basis.
i'd only worry about a/b/g if you need access 100% of the time, and if access is that essential, you might want to look into a cell phone plan that lets you use that for access in a pinch.