Puzzled... Las Vegas and especially the Grand Ganyon are not good choices if you're expecting decent weather in February. The Grand Canyon's South Rim (where most visitors go) is 7,000 feet above sea level the North Rim is 8,000 and not even open except May to October. Always go prepared for cold weather ...
Las Vegas can be really hot in the summer... 110 degrees (F) in the daytime is not uncommon. But, as with most desert climates, it loses heat really quickly when the sun goes down. Even in summer, away from the paved heat sink that is most of Las Vegas, temperatures drop rapidly to less than 50 degrees...