Antiquarium is a great place! My wife gave me an antique map of Houston, Downtown circa mid-late 1800s not the Heights, from there for christmas and they were very helpful. Also last time I was in Dramatika, the framing shop on 19th, they had a great historical map of the Heights framed and for sale. Apparently there used to be a really nice park just north of 19th street, near where krogers is today if I remember the map correctly. This is the only historical map of the heights I've seen personally.
So you may want to check out Dramatika as well, but you'll have to beat me to it! That is if I can convince my wife that maps on all our walls WOULD indeed look nice!