I used to go to Vegas alone, but that was because I'm a poker player. You could easily do that alone for long hours.

Now I live in Vegas.

I would say that most of the things on the strip are still more suitable as group activities. It might feel a little weird to go to a nice restaurant alone or bar alone.

If you just want to eat some fast food/cafe style good, get some sun, or walk/shop around a little bit, that's fine for doing alone. Or even seeing a show.