I don't know how I missed this. Sorry.
Here's my take:
1100 Franklin Dr - Nice neighborhood, but there are some renters in the area and the street has its share of problems with speeders, because it cuts through from Ranch Road 12 to Bishop. The train tracks are near everything. This is about as far from them as you're going to get.
104 Panorama Dr - This is a nicer neighborhood than Franklin and not a through street. Probably not a lot of renters here.
Cross - I know some people who live out on this side of town and love it. I prefer the hills around RR12, but this is almost surely quieter.
80 Elm Hill Ct - Not where I would go. LBJ is busy and plagued by speeders and drunk drivers and there are lots of rental properties nearby and KB Homes, which are not much better.
Nichols Dr. - See Elm Hill Ct. Without the street number, I can't say how close it is to LBJ, but it is not where I would live.
208 Valero Dr - I think this is east of 35. I don't know much about the various neighborhoods over there, but it is too flat for me.
We don't have the multi-family houses that I think you are thinking of (3 floors, with one family/generation on each floor). We do have 15 students crammed into a 4-bedroom house, though. OK, maybe not 15, but sometimes quite a few.
I'm no realtor, but I have lived in San Marcos next to forever and I own a home not far from some of those neighborhoods.