We're going in July to celebrate my hubby's 40th! I have found that purchasing air and hotel separate is cheaper than a package and offers you greater flexibility. If you can fly out of the US (ie Buffalo) it is even cheaper. Check Jet Blue for flights to LV and you might find a cheap flight. If you can wait to go in the summer months, you will find amazing deals on hotels, especially if you go Sun-Thurs. If you sign up on the hotel's website to be on their mailing list, they will send you periodic updates on specials. We did book our flights this past Oct because we fly on points, but I have seen reasonable airfare out of Buffalo. I will wait until the summer promotions come out for cheap hotel rates. Good luck planning, and tell your husband that he won't regret going....we love it and have gone every year for the last 4 years. We can't get enough of that place!
By the way, his bday is also in May, but we are postponing the celebration until the summer to take advantage of the cheap hotel rates. We went in May one year, and although the temps were nice, it was certainly a lot more pricier than our summer stays. I don't mind the dry desert heat either....