i have a similar problem. i live in urban houston and looking for places to search for antiquated items are few and far between as far as i am concerned. my living area of houston is still young. houses are 50-60 years. the oldest coins i have found have been a couple of 28 and 29 wheaties.
something i consider when deciding to MD is the age of the area's buildings or near-by buildings. honestly the areas that have been built up in the last 50 years here are built up a foot or more because of our addiction to flooding (makes the streets hold the water instead of your living room). this makes it hard to find anything over the age of your neighborhood simply because the man-made build up is anywhere from 1'-3' feet of clay/sand.
Finding anything in urban areas here usually requires a pocket-sized or larger back-hoe.
many small towns have just a 'main' street or 3-4 square blocks of business and thats it. you check the edges of side walks and between the buildings. old old old old old bridges are a favorite of mine. i love em. i have found all sorts or neat bottles and old jars with just my eyes. found a bunch of bullets buried in the sand the other day.
look for side walk excavations and search the bed. dont tell any one, but, historical markers on highways are not always at the exact location. search an area wide around it, as long as its public land.......

i will soon be hunting for an old spanish mission site near a river here.
if you live areas where the near-by woods are filled with small trees it is a good chance that it has been dozed over a while back and the trees are still young which makes for a lot of painful digging because of the thousands of roots. find areas with large trees representing old growth and you will have easier digs with less roots.
river banks with some shoreline are also worth a look. even if it it not a people-traffic spot.
the brazos river in San Felipe has yeilded many relics and coin finds. When Stephen F. Austin first brought his people to that place a ferry was built there. It was the only places to cross that river in east or west for many many miles. to this day finds are still made all the time.
search for the age of bridges in your area. many are very old and were at one time hop, skip, jump paths across creeks and rivers.
i'm no expert this is just what i think of when trying somewhere new. but, sometimes i just find open fields to sweat in because i get stir crazy.