Maggiew43 - WOW!!! That's a multi-leveled answer! LOL :)
When you say you will be working from Valencia to Fresno, does that mean you will be commuting from Valencia to Fresno? What does that mean exactly. From Valencia to Fresno is quite a commute even if you only do it once in awhile; that's about a 3hr commute - ONE WAY!!!
Even the valley to Culver City is quite a commute depending on the time of day you will be traveling. Either way, you want to probably be on the east side of the valley because that is the part of the valley that is most accessible to the 405 freeway and the 5 freeway, which are the main routes to both Culver City (the 405 freeway) and Valencia and Fresno (the 5 freeway).
The valley is a pretty large metropolis and pretty much anywhere you live you are going to be close to restaurants and shopping and entertainment. A great place for would be Toluca Lake, Studio City or Sherman Oaks. However, because these are high demand areas, they are also rather pricey and you're not going to get as much bang for your buck as far as housing space as you would say in the north valley like San Fernando or Sylmar or North Hollywood.
Where in the valley you live will be really dependent on how much you can afford and whether you rent or buy. Right now, many prospective homeowners can buy a modest home in the valley for the same or less than they would pay to rent that home. The rental market here is actually just as active as our buying market.
Without more info, it's hard to say what area you are going to be able to afford to live in. If you would like, please feel free to contact me for more info.