Another vote for Southern Utah, bryce canyon, lake powell, and mushroom valley are not to be missed. Here is the deal with the weather. It can be 70 and sunny during the day and all you need is a tee shirt and shorts but will get very cold at night. If a front comes through and they get dumped on then head to northern utah and ski the powder, you will not find any better. I go out often in March/April as I can ski powder in the morning and golf in the afternoon. If you don't ski then you probably wouldn't be as happy to see 2 feet of fresh powder as I would. Just check the weather in advance and adjust your plans to fit the weather.