Some food for thought.
Unless you plan on riding trails, a mountain bike may not be your best bet.
Do you plan to ride mostly on the road, off road or a combo?
My primary ride is considered a comfort bike (Giant Sedona DX) and would fit your budget, it is betwen a mountain bike and a street bike. However, if off road riding will be minimal and/or rail trails, I would actually suggest Giant's Cypress line to get the 700c wheels.
Each manufacturer has their own similar lines of bikes.
If you will always be on the road, but don't want drop bars, then a hybrid would be in order. Narrower tires, but flat bars...
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Slow Ride Cyclists of NEPA
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