Nothing is said in canon about Hogsmeade's surroundings. Since it is within walking distance of Hogwarts, it can be assumed that the setting is similar.
Here is a map of Hogwarts drawn by J.K. Rowling:
PHP Code:
http://www.hp-lexicon.org/images/jkr/jkr-hogwartsmap.JPG
It depicts Hogsmeade to the northwest of Hogwarts, and away from the forest. The town could be surrounded by open grassland, given the space between the forest and Hogsmeade, but we can't see anything past the corner of the page. I think you would be safe just making up the surroundings, as long as it is nothing outlandish.
The Shrieking Shack doesn't appear on Rowling's map, but I think you could safely place it anywhere near the town.
The Three Broomsticks could be anywhere in Hogsmeade – it's specific location in the town is not specified. You would be safe putting it anywhere in Hogsmeade you like.
Tim the Enchanter