I havent joined Gold Country Breweres Association but I've heard a ton of good things and if my work schedule didnt interfere I would so be at their meetings!
We get a majority of our supplies from Brew Ferment Distill in Oak Park on Broadway, Tim and his brother are great and always helpful. Plus he usually has a few beers on tap, free to drink
We've also made a few brief stops to Folsom/Roseville Brewmiester when BFD doesnt have what we need/want.
If you're new to the area I would check out the Raley Field Brew Fest, Capitol Brew fest, Sac Beer Week and the NorCal Brew Fest. Its a great place to meet new people in the area.
There have a been a ton of new microbreweries opening up in the area the past 2 years or so. Loomis Basin in Loomis is great, good beer and they teach all grain classes and the owner is really nice. Love Rubicon in Midtown, American River Brewing in Rancho Cordova, Lockdown Brewing which has a room in Old Town Folsom and Rancho Cordova. Another new one is Track 7 which I haven't tried yet but have heard great things is somewhere over in Land Park area. And of course theres also River City Brewing which has been around for quite some time.
As far as tap selection and tap rooms... theres always the Yardhouse in Roseville. Samual Hornes in Folsom is good, lots of beer selections although I feel the atmosphere/staff could be more inviting. And Final Gravity which just opened in July up I guess its technically Roseville on Sierra College Blvd, went there for the first time last night. They have a lot of different stuff on tap and its always rotating. Great place to watch sports, they also have a ton of boardgames, the staff was super friendly and helpful and it just seems like a great place to spend a few hours hanging out with friends playing games or watching sports.
Hope this helps. Welcome to Sac... Its a great place for beer =)