Thanks for all of your suggestions, everyone!
I've already announced the location as Americana on Society of Illustrators of LA blog and Illustration.org, so we can still meet there at 10:30 and meander off to somewhere nearby later...LA Equestrian Center sounds fascinating - drawing horses would be a challenge!
monking, I hear you about non-walkability of LA. I usually walk or bike within my town, and would be interested in exploring other parts of city on foot. As a side note, here's an interesting photo journal: http://walkinginla.com/