Some of my favorite place are:
The Hofbrau House, but that place is huge you can most likely do a walk in.
Andre's at the Monte Carlo is really fancy French style food. I've always left in a food coma, but their soufflés are to die for.
Anything at the Bellagio, I've been to Le Cirque, Picasso and the Steakhouse.
I wasn't so impressed with Emeril's Fishouse, but his Steakhouse was great.
At the Rio is a Napa something restaurant that was really good, but I haven't been there in over 10 years. All the Celebrity Chefs have numerous restaurants, but I doubt they ever really go to them. For an awesome breakfast try one of the Blueberry Hill coffee shops. There are two on Flamingo (I think) they have big fluffy pancakes, and giant portions.
You guys might like the Harley Davidson cafe. Down home food and the "decor" is bikes, so you'd have lots to drool over while waiting for your food.
There are so many choices it can be overwhelming. On our trip we are only making one reservation at Del Frisco's steakhouse. Fran really likes their onion rings and their Wagyu Rib eye is pretty awesome, not to mention the Oysters and molten chocolate cake....everything we had there was tasty.