San Antonio Winery in downtown LA is gorgeous. I went to a reception there and it was just beautiful inside!
The Point Vincente Interpretive Center in Palos Verdes is also beautiful, especially if you are having a summer wedding, they have an ocean/Catalina Island view to die for!
Michael's Restaurant in Santa Monica also does both ceremony/reception at the same location, best for weddings on the smaller side.
We had our wedding at the LA River Center and it was beautiful and could accommodate for both ceremony and reception, and we had about 150 guests as well. You are definitely not short on options since you are having such a small affair!
Depending on your budget, Wattles mansion and Greystone mansion are also incredibly gorgeous locations in the Los Angeles area!! You definitely have to go out and look at a lot of places before you decide. Pictures just don't do some of these places justice!!
I recommend the Inn of the Seventh Ray in Topanga Cyn. I had my wedding there last year in November. It is a beautiful location. We had our ceremony and reception there. The food is very good and mostly organic. They make the cake, or you can bring yours. I had their vegan blueberry cake that was delicious. Here is there website: http://www.innoftheseventhray.com/ Sonia
there's the Japanese Garden at Kenneth Hahn Regional Park. I has a waterfall and a beautiful view of Los Angeles since it's situated in the side of the hills. The venue is also REALLY cheap at $475 or so. I have more information but it's not on me right now (sorry). I was going to have my wedding there but the space was too small. But it is soooo romantic. Perfect for an evening wedding outdoors. Just contact the park for more info.