I'll address this from the angle of a guy who's about to turn 30 and his wife arranged him a trip to Vegas. The reason for this is because I'm about to turn 30 and my wife just surprised me with a trip to Vegas last month.
When she told me she's "made arrangements" for us to head out there, I was partly thrilled and partly thinking... "God I hope she picked a great spot on the strip". When she handed me the Encore envelope confirming our stay you couldn't have slapped the grin off my face
Keep in mind this wasn't our first trip, but as a couple around your age that doesn't have kids (and therefore, expendable income), I can only say that if money is an issue, I'd shorten the trip and do it big rather than skimp on things throughout the week. Everything in Vegas is designed to extract money from your pocket, but you will never experience better service or have more interesting experiences than what is there for the taking in Vegas.