Ask yourself two questions. Have you seen many other properties with the type of expansion you're thinking of providing? Does this make your home materially different from others in your neighborhood?
Although there is always a range of buyers, in terms of taste, the trend in Arlington has been for buyers to look for the more standard floor plans and to want to purchase at the midpoint of the neighborhood. Renovations that provide open spaces on the main level are in vogue, ones that simply provide more bedrooms are not so much. Significant changes in appearance for the neighborhood, such as changing the faÃ§ade to look contemporary in a traditional neighborhood, poses problems for the seller. It's not that no one will purchase houses that are unique, it's just that the pool of buyers is smaller.
Trying to visualize adding a full story to a 1.5 story bungalow is difficult, but, it suggests a colonial with a taller than wide aspect. If the front elevation is also changed to present a colonial appearance and the main floor is opened, the neighborhood isn't only bungalows and ramblers, you plan on living in the property for several years, and the costs make sense, this should be a reasonable project.
Finally, we encourage friends and clients who ask this type of question to consider what their house would sell for plus the cost of the renovation, and then to look at prices for a new home with the amenities they'd be adding, before starting on this kind of adventure.
Hope this helps.