Firefly is the one Vegas restaurant we always make sure to take family and friends that visit. The food is absolutely incredible, the drinks are great, atmosphere is nice, it's pretty cheap (especially for the quality you get), and it's open late.
My go-to favorites are the tortilla a la española, stuffed peppers, manchego mac 'n' cheese, and petite filet. The tortilla a la española has just the right amount of spiciness, the stuffed peppers are bursting with flavor, and the mac 'n' cheese is the best I've ever had (and I try the mac 'n' cheese everywhere I go).
For drinks, the blood orange mojito and white sangria are absolute must-haves.
The service has always been great.
It tends to be pretty empty during the day, but can get quite crowded in the evenings.
And they're great about accommodating large groups.