The PHOF is very cool. I want to check out their new location next time I'm in Vegas.
Momofuku has some of the best noodles I've ever had. Pretty reasonable process for a strip restaurant also.
I haven't eaten at Secret Pizza because there's always a ridiculous wait to get in when I've been in the area. Sorry, don't care how good a pizza is, I'm not waiting 2 hours to get a seat.
If you like buffets, Wicked Spoon is a little spendy ($55) but very good quality.
Eggslut is a dumb name but excellent breakfast sandwiches.
The Cosmo is next the Bellagio, so you can go there and see the fountain show or the conservatory if you want something free to do.
Across the street from there is Paris, you can go up the Eiffel Tower, I forget how much it costs, but it's a nice view.
About a block north is the Linq, they have a promenade with lots of bars/restaurants and the High Roller observation wheel and zipline.
New York has a decent arcade and a roller coaster that goes in and outside of the casino.
You will probably want to leave Vegas pretty early. I-15 to LA can get very backed up and a 4 hour drive can become twice that.