Vegas is a tricky one, I have been with friends and also just with Mrs on couple occasions for 3nights 5 nights and 7 nights, I love the place, but, it's hugely overrated, it's tricky because it's along way to go for 3 nights, but there's only so much you can see and do, sure you can take in the shows, gamble, go on tours and drink the day away, but 7 nights I got bored even 5 nights you have seen everything. When people ask me about Vegas, I say go for 5 nights but make sure you pad your time out with shows and tours everyday, otherwise your going to wish you spent the money on a fortnight in Spain or a week in Thailand