Oh my god. 6 days is an eternity in Vegas.
Vegas has some of the best food in the world. So please please don't just eat the McDonald's in the food court.
Definitely stay on the strip if you can. I've stayed off strip before and it's just not the same. You can just drive or taxi over to the downtown old Vegas area if you want to check it out. But it's nice staying on the strip if only to walk around at night, see the Bellagio water show, get huge pitchers of margaritas and just enjoy the crazy sites. If you must do a buffet, do the one at the Wynn. Everything else sucks balls and is so pricey. Set a budget for yourself if you're going to gamble and don't go over that budget. Don't be that guy. Catch a show if you can. Cirque du Soleil is really smurfing cool.