1940s noir research in LA--possibly in person soon

I’m thinking about taking a trip out to LA to do a little research for the murder mystery I’m trying to write, featuring several Hollywood scriptwriters of the year 1940. Of course I understand how much of 1940s LA has disappeared, but I am such a topographically inclined writer to begin with, and I’ve spent only a few hours in LA in my lifetime, most of them asleep, that I feel this trip is necessary. Plus my detective is a lifelong NYer, like me, who comes out to LA for the first time in HIS life in early spring, so I think that’s what I’m shooting for. Let’s say, March.

Can any Angelenos recommend a commercial tour of the Hollywood Boulevard area (near where Schwab’s, the Garden of Allah, etc. used to be)? Is there anyone personally knowledgable who’d be willing to swap such a tour with me for a similar tour of Manhattan sometime? (I’ve led literary walking tours of lower Manhattan for years now, some taken by Dopers who seemed entertained.) Anyone who knows an affordable hotel, or a b and b in that area? Anyone want to share their own expertise with me, either in person when I get there or right here online? I’m thinking I’m going to be there for maybe four or five days, and apart from interviewing some people who used to work in Hollywood during that period, I’m going to want to fit in a lot of sightseeing of this sort, just to get a feel for the area, the atmosphere, etc. (I’ll stay longer if I can find cheap enough digs–I’m going to try to get my university to pick up the tab for this research, and I’m figuring on spending $1000, including travel, lodging, car rental and food, so it looks four days should tap me out.) Any other suggestions will be appreciated.