I would check out craigs list and buy a mid to late 90's rigid mtb. Then I would put on road tires and you will have a reasonable light bike that can go most places.
If you want to go new check out the Giant Sedona or the Giant Roam.
Sedona (2016) | Giant Bicycles | United States $360
Sedona DX (2016) | Giant Bicycles | United States $440