LAX area is probably the best because it’s very freeway accessible.  Hollywood is a nightmare.

Pretty much stick to the East San Fernando Valley area (Sherman Oaks/Burbank).  Traffic being what it is, it can easily take 30 min to over an hour to get  to LAX or dtla from my area and these days I'm just not into doing that.

Think of where the 405 and 10 cross. That general area is where you want to be. Slightly closure to LAX. You'll have the Santa Monica, WLA, and Beverly Hills crowd. That's where the dinero is. Avoid DTLA, the Valley, both Valleys. Pasadena,Glendale,South Bay and the IE.
As for me, I avoid all the places I mentions that are favorable because I'm closure to the IE and would hate the drive.
Newport Beach would be ok for a short stay.

As you said, LA is HUGE. The city covers more than 500 square miles. And LA county covers more than 4,000 square miles.  
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So where are the clients you most want to book?  
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You can think of the area in three major segments:  
1. LA City central and surrounding areas: This covers LAX to the west, Hollywood, Downtown, and Bev Hills in the middle,  and out to Pasadena to the east/north-east.
2. South LA: this covers Inglewood/LAX to the west, Huntington Park/Downey in the middle and Pica Rivera/Whittier to the west.  
3. San Fernando Valley: This is a large area (as big as a separate city) north and west of LA city spanning from Woodland Hills (or even Thousand Oaks) to the west, Northridge, Encino, Van Nuys in the middle and Sherman Oaks, North Hollywood, Burbank to the east/
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#1 is where most white collar businesses are, and contains high-price real estate areas
#2 is where most of the more affluent people live who are tired of city life.  
#3 is mostly lower level income areas.  
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Most touring providers tend to stay in #1. But I think they are missing many opportunities to attract clients from the Valley.  Those clients who live and work in the Valley generally won't want to take the time and hassle to travel into the city (could be as much as 3 hours of traffic, round trip).  
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 I placed a link to a map of the overall area.. hope it works.  
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Life is good
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The Cat

Just saw your reviews/website!  You can work out of my house on the west side!  Just kidding, as my g.f. would never allow it, but WOW....!

Seriously, WLA works for many near LAX, WLA, SM, LA...even West Hollywood is not far.  But it is always hard to say what is best for a visiting lady....

I believe the previous poster has his comments on 2 & 3 the reverse of what he intended.

there are tons of multimillion dollar properties in Encino, Sherman Oaks, Tarzana and Studio City.  

i know people in the valley like to think there is money there but if they REALLY had money they would have stayed in Beverly Hills  LOL   ..  ok so ...   i would second what Hpygolky said ....West LA along the 405 near the 10 area ..  that way besides the 100s of west side guys who can afford you can easily reach as well as the eight or nine guys in the valley          i wouldn't stay in west Hollywood or Beverly hills , traffic awful plus guys could accidentally run into a wife's friend.    while West LA hotels arent fancy but a lot less $$$ ...    (ok valley guys just teasing !!)