Lake Havasu is a great place to visit and they have just about every type of campground in that area you might be interested in. The "lake" is actually a long wide place in the Colorado River created by Parker Dam. There will be lots of water for you. One of their highlights is
London Bridge.Las Vegas is up the road to the north and beyond that is Death Valley. March would be a great time to visit DV but that's a favorite month there so it will be busy. Camping with hookups is limited in DV.
The Grand Canyon is not all that far off to the northeast either. But it could be somewhat cold up there yet in March since it's at 7,000 foot altitude. March high - low temps typically are 51 - 25 in March. You would be at the mercy of weather conditions that particular week when there in March.
You will like Lake Havasu. It's a little oasis in the middle of a very dry desert area.