As far as planted tanks go i would try eye candy aquariums, i think its in buena park. They have good knowledge in freshwater stuff, most stores I've been to seem to focus more on reef stuff, and they have a few nicely planted freshwater tanks, there a bit on the expensive side if you decide to buy stuff though. Ive also heard A+ aquariums in el monte is good but i haunt had a chance to get there.
For knowledge of fish and plants, forums like this and google are your best bet. LFS workers does not know much at all.
As far as seeing many different variety of fish, I would try Tong's in Fountain Valley.
Eye Candy is in Garden Grove and I don't think they know much about plants or freshwater stuff. They are more into salts.
A+ caters to nano fish and has some selection of plants. They will bring in those uncommon fish. They are a sponsor on SCAPE. They would post what's new or members would update what they have in stock when they stopped by.
Nature aquarium in Santa Monica is a good place to go. They have ADA tanks and display
I;m looking for plants mainly... to be honest I really couldnt care less about the employees knowledge... Thats why I'm on here!! I just wanna see these thiings in person So I have a better I dea of what to put in my scapes.
Wheres A+? I;m in huge need of nano fish..