I also have WiFi issues. I almost always have to re-connect to my home network after I close a session and try to access Safari again (ie, surf the web, play a game or read a book, then try to surf the web again= reconnect). Two laptops and and two iPhones sitting in the same room (6 ft from the router) with no connectivity issues.
I was originally using WEP but switched to WPA2. No difference.
I've tried the screen brightness "fix". No difference.
It's annoying but, to be honest, it's still faster than booting up my PC laptop! And it's a much more enjoyable experience.