We were looking at the hop on hop off bus however I feel like it's a waste of $. We really are only looking at doing things around the Mall area such as the Smithsonian Air and Space Museum and possibly the Spy Museum. The only thing we'd need transportation to would be the Pentagon and we could take the subway for that. Is it doable to walk around the mall area? It looks like it's only a 34 minute walk between the Lincoln Memorial and the Air and Space Museum. We'd have stops in between so seems doable to me. Opinions please.
The short answer: no, the hop-on hop-off bus is usually not worth it if your main plans are around the National Mall. Nearly everything you listed is walkable, and DC’s Mall area is designed for pedestrians. Most visitors find that they don’t need paid sightseeing buses unless they want narration, a relaxing overview, or plan to visit attractions far outside the Mall.
The National Mall is long, but flat, open, and full of monuments, museums, and grassy rest areas. A walk from the Lincoln Memorial to the Air and Space Museum is indeed around 30–35 minutes, and you’ll naturally stop at memorials and museums along the way. It’s one of the most popular and scenic walks in the city.
Because of your itinerary and needs, a hop-on hop-off bus won't offer significant advantages. Here’s a breakdown of why:
If you prefer a little extra convenience, there are other ways to shorten the walking without the cost of a hop-on hop-off pass.
Alternative transportation options that work better:
In general, the Mall is very doable on foot, and most travelers enjoy the freedom of wandering without having to time their plans around a bus loop. The hop-on hop-off options are best for people who have mobility challenges, want guided narration, or are trying to hit many distant neighborhoods in one day.
For your specific itinerary—mostly Mall museums plus the Pentagon via Metro—you’ll save money and probably have a smoother day simply walking and using Metro when needed.