I've spent a lot of time in Vegas over the years (husband was for years a professional poker player) so I'm happy to give advice. You did the right thing to hire a car for the stay.
Two weeks ON THE STRIP is a long time, but there's loads to do off it as well.
Go for a hike in Red Rocks on the edge of town, it's easy to get to and it's beautiful. Just make sure to take all the usual precautions and be VERY vigilant about sun protection and staying hydrated. Going early is best unless it's winter.
Most food on the Strip is overpriced and average. You're paying hotel prices. There are some decent restaurants in the hotels, but they just cost so much for what you get. However, for a special night out pretty much any resto at the Cosmopolitan will be very good, Venetian/Palazzo, MGM Grand, Caesars.
If you like Asian food, there are LOADS of excellent restaurants that don't cost a lot in nearby Chinatown. Lamaii has fantastic Thai, Monta has wonderful ramen, Kabuto has a superlative edomae sushi tasting experience (you need to book), Naked Fish a bit further afield has more the fun and crazy sushi rolls experience but still high quality. Several excellent Vietnamese and Ethiopian (yes, I know not Asian) if you want to branch out and for top notch spicy Szechuan Chengdu Taste is great.
If you love seafood Hot n Juicy in Chinatown is a lot of fun. They do an incredible seafood boil with side dishes and local craft beers.
If you reply asking for more recommendations about what you enjoy, I'll be happy to give more recommendations as there is no shortage of excellent value casual dining in Vegas. You'd be amazed just driving past what looks like a dull strip mall how many of them will have excellent quality food.
If you're a breakfast lover, Vegas is HEAVEN. Mr. Mamma's and BabyStacks are my favourites. The latter has Hawaiian style items on the menu as well, such as Kalua pork and fried rice omelettes, Loco Moco and dozens of delicious pancake varieties. Skinny Fats has very healthy as well as indulgent options and they make good fresh pressed juices. Go early because these places are very popular with locals. They're a zoo on the weekends.
A few other random recommendations: The Neon Museum. Go at night when it's all lit up.
The Fireside Lounge in the Peppermill Restaurant. The food isn't much to write home about but the cocktails are good and the lounge has been preserved in amber from the 70's, it's a really fun throwback.
Lots of quality vegetarian and vegan food. Violette's Vegan is my favourite.
Capo's Italian Speakeasy. Fun experience, the food is good with large portions. Old school Italian American red sauce joint.
Other Mama has a varied menu with portions for sharing. Excellent seafood especially. Oysters, crudos, etc. Great cocktails.