Just to throw in my 2 coppers:
1) Last Grenadier: Haven't been in years, mainly because they have an annoying habit of closing early on weeknights after people who have jobs and can actually afford to buy stuff get off work.
2) Aerohobbies: Just made my first visit a few weeks ago and was just completely shocked. The store is absolutely insane. In addition to about 10 copies of every current RPG book on the market, I found old 20 year old out-of-print copies of stuff in the same pile as stuff that literally came out that same week. And, as someone mentioned, it's all "neatly" piled on the floor for your browsing pleasure. In addition to the piles of RPG books, I found one old shoe, a beat-up pair of roller-blades, a half-eaten sandwich, a huge box of waterlogged and water-damaged RPG books that had mildewed and smelled awful, piles and piles of old magazines and books (some fantasy-related, some not), a broken industrial-size fire extinguisher, and a glass display case that was broken and full of trash. I felt like Indiana Jones, except without the snappy fedora. While digging through a pile of stuff, I was startled at one point when I looked up and noticed a guy standing next to me (he was the only other person in the store). I had no idea how long he was standing there. He said, "Well, it's about that time." I said, "Time for what". His reply was "We close at 6:00." WHAT? What's the point of being open if you're going to close at 6pm? That's particularly true in a place like LA where it takes 30 minutes to get anywhere, and twice that long during rush-hour. There's no way an employed person could get to this guy's store during the week. This is no shortage of things I can say about this place. It was quite the surreal experience.
3) GameZone: I'd say that the staff will completely ignore you, but one of the women in my group recently went in to buy something for a friend and was given quite a bit of personal attention. She did mention to the guy that perhaps it was time to air the place out a little and fumigate to get rid of the "man-funk". One of the worst smelling places I've ever been into, and that includes the time that I got a tour of Pedigree's dog and cat food packing plant.
4) All Star Games: Despite being in "the 909", this was a great store with super friendly and knowledgeable staff. My only beef with this place is that they are "shrink-wrap happy". It's annoying. If I can't flip through a book before I buy, I might as well buy it online, cheaper, and save on gas money driving out there.
So, there you have my mini-review on LA game stores. Good luck.