Go in the evening! The lights are mesmerizing and are a true show.
Fremont Street is less formal and more casual, you will find more interesting characters on Fremont than on the Strip. Most people here will have lots of liquid courage since the drinks here are big and strong and you won't be able to walk a block without having the opportunity to buy a drink. The original hotels of Vegas with all the classic décor. Both Fremont and the Strip are great experiences and completely different. You'll find less expensive and still quality food on Fremont. This is where you will find the true grit of Vegas - I love the "real" feel found here.
Take the bus if you're staying on the Strip, it's cheep and will save on the taxi or rental car costs.