There are plenty of very nice restaurants in Vegas. Pick a nice one with the kind of food you like and do that one night.
A couple of decent places off the beaten path are the Breakfast Buffet at the Orleans on West Tropincana. It's priced decently and the food is pretty good.
The Black Bear, also on Tropicana is a good place to get a good Breakfast as well.
Ellis Island is a good inexpensive place to eat as well. Nice little steak cooked well. There is a Micro Brewery there so if you want a beer, you can get that too. Also, there is a little BBQ place right there in the same location that I like. Decent BBQ and Chicken all fairly inexpensive. It's on Koval there in Eastside.
The Sandwich Earl there on South Vegas Blvd is good. It's a sandwich place but it's pretty good.
People will say Heart Attack Grill but if you want a good burger, the Burger Bar is close and it's a good burger. It's in the Madalay Bay.
If you like Seafood or Asian, Sushi, that kind of thing then Roy's is a good place. It's a romantic type setting if that's the kind of food you like. Roy's is on East Flamingo.
Vic and Anthoney's is good, I've eaten there many times. It's expesnive, it's Steak, Seafood, upscale. It would be a very nice place for a special occasion. It's on Fremont St.
If you like Greek Food, there is a place called the Fat Greek. It's pretty good if you like Greek Food. It's not over priced and I've always gotten really good service there, which is a big thing in Vegas. It's on Decatur.
If you like Italina Food, Casa De Amore is a good place. It's off the beaten path as well. You can eat in the formal dinning room or you can order at the Bar which is also not bad and listen to live music. It's kind of cool to do that. My Wife likes that. It's not real, real expensive and the food, I think, is really good. It's on East Tropicana.
There is also a place called Off The Strip. It's also Italian and it's pretty good too. We don't go there as much because my Wife likes the Music at De Amore but a lot of locals go there. It's more of a neighborhood place. People don't dress up and it's not formal. It's just a good place to eat and not very expensive. It's out on South Highland Parkway.
If you like French, which I am just so-so on, I am told that Le Crique is the place. I can not say as I have never eaten here but I have several good friends and family that have said it is very good. Also very expensive. It's a special occasion kind of thing, very Romantic I'm told. It's in the Bellagio.
If you want to shop, you can go out towards the AP and there is an outlet mall that you can go to which will be priced much better then on the strip or what have you. If you want to make a day of it, you can plan a drive out to Stateline for the outlet mall there. It is bigger with more shops and priced better because it is further out. In these places, you can find just about anything you would want.
I hope this is helpful.