You don't have to come in the summer to see them. They are here year around. A little earlier in the year might get you into their blooming season (Mid May to Mid June) besides avoiding some of the heat. June is the hottest month of the year to be in Arizona. We were here when it was 122 in June. Need I say more. Definitely hotel it. When ever you decide to come drink LOTS of water all the time, wear sun screen all the time and be aware you can burn in under 7 minutes even with sunscreen. Otherwise it's beautiful during that time of year. The desert is amazing after a rain!!
Dave