"Chillon! thy prison is a holy place, / And thy sad floor an altar" wrote Lord Byron, the father of the Romantic movement (and also the father of the first programmer Ada Lovelace). Whenever you crawl a dungeon in Descent, Dungeons&Dragons or Baldur's Gate, you are retracing the 1816 poet's visit to Château de Chillon on Lake Geneva.
There is a fine balance in making a tabletop hill the right mix of a gaming token, a unit display stand and an eye-candy. When you let it slide in one of the directions it will lose its unique capabilities of elevating your wargaming experience to the next (excuse the pun) layer.
A swamp and its family and relations are rarely seen and that is a pity as they offers interesting strategic challenges. Seem to favour static armies with a lot of guns where in fact it can also become a deadly trap if the enemy manages to outflank you?