Honestly, it depends on what you like to do- shopping, fine dining, shows, clubs, etc. Typically, my husband and I have btwn $800-$1000 total for a 3 night stay (keep in mind we gamble and like fine dining). That’s $400-$500 each. You can save alot by signing up for casino cards but you would need to gamble a bit to get the freebies. You can check show tickets half price from ticket booths on the strip and if you are willing to dedicate t least 2 hours to a timeshare presentation you can get all kinds of stuff. We have gotten cash, dinners, gondola rides, free admission to Madam Tussuad’s Wax Museum, show tickets just for attending.
It all depends on your personal taste and how much you gamble.
Just a general guess is about 600 to 700$ cash.
You can get buy on very little on Vegas once you figure out how they city works, but it also can zap your money ever faster.