I don't think these issues go so much to the point of needing a "startup lawyer" with a presence in the Valley, but more to getting high quality service, which

I don't think these issues go so much to the point of needing a "startup lawyer" with a presence in the Valley, but more to getting high quality service, which probably means paying $$. A first year associate knows next to nothing about practicing law, and shouldn't be let anywhere near your business. While it's possible that Wilson Sonsini does a better job of handholding their first year class, I doubt that the quality of work you'd get from a first year at X top firm differs significantly in quality from that of a first year at top firm Y. Likewise, a partner in the corporate practice group at any major law firm would probably not have made these mistakes, regardless of the firms profile in the Valley.