Kimchee, I go a couple of times a year, for the last 20 years or so, and just got back week before last. We love that town!
If you ask 100 people, you'll get a hundred different answers, but I'll tell you how we like to do Vegas.
Are you on the strip or downtown? Fremont st (downtown) is much more affordable, and if you want to eat at a nice restaurant, go to Binions ranch, on the 24th floor of Binions hotel/casino. Make your reservation for after dark because its all glass and the view of the city at night makes for a magical backdrop for an excellent meal. I'm not a fan of lobster, but my wife would leave me if she didn't get one of their chicken fried lobster tails when we are there. She describes it as "heaven on a plate". Myself, I opt for one of their melt-in-your-mouth ribeyes. In 20 years, I have never had a bad meal, or service there.
There is so much to see and do its overwhelming. Try and plan out your daily excursions to avoid redundant cab rides, as that gets expensive rather quick. You can take advantage of "the deuce" a double decker bus that goes between downtown and the strip, and its 7$ per person for the entire day. Be warned though-it makes a lot of stops, and isn't always there when you want it to be. Theres also a monorail that travels the length of the strip-you can buy an all day ticket and ride as much as you like between the Sahara and MGM grand, and it stops at all the major hotels along theway. Its very fast and efficient.
The "The sirens of TI" (treasure island) is a free outdoor show in the evenings that is neat to see, as is the erupting volcano right next door at the Mirage. As far as buffets go, The Rio has a really good one, and if your downtown, while its not as flashy, The Main Street station also has a very good one, and its quite a bit cheaper. As far as "best slots" (?) go, We have a lot of luck downtown, particularly at the Four Queens lately. I like "Pinball" and "Top dollar" machines-they are usually pretty good to us, and this last trip was no exception-our last day there, we paid for our entire trip!
I could go on, but theres so much to see and do, its literally sensory overload. When you get to your room, there will be a "Whats on" magazine there-use it. Its divided into catagories like dining, shows, gambling etc, and has a nice little map if your unfamiliar with the town. Grab a Starbucks, sit down and go though it and plan out your day. And don't be afraid to ask the hotel employees if your not sure about something-it seems most are happy to help!
Have fun-I wish I was going!