It's not a bad idea. Laying the same floor throughout the house will make it look more spacious, especially if it's all laid in the same direction. Flooring direction can be affected by structural considerations in addition to cosmetic ones.
As far as color goes, a light color might be better for a smaller house, particularly if there's smaller rooms and limited light. Wall color, area rugs and furnishings should be taken into account.

Relatively speaking, the cost to do so might not be proportionate to the selling price, and I would expect most people shopping homes in that size range are not expecting hardwood.

Having said that, we are replacing all the carpet in the home we just bought with hardwood and our last home was all hardwood. We would have it no other way, but it's expensive, and most people don't care and won't spend the money, so come selling time, it's a loser.