Breakfast, lunch, dinner, pre-club, or post-club as the sun is rising, Earl of Sandwich is good 24/7.
Probably one of the best value-priced meals on the strip. So cheap, simple, but well executed. Also, more than likely you'll encounter a massive line. Don't worry, it does move relatively quickly, so just wait!
The menu is also pretty big, but my favorites are the original and Italian.