I am allerigic to nearly all kinds of sun screen and aloe, so I have to be really, really careful when in the sun (and I like being outdoors, a lot).
Nike, Reebok and several others make light-weight, breathable and with sun protection shirts and pants. I've also found some at LL Bean. Many of these are long-sleeve and they are not to hot for me. Check the work out sections of Kohl's, Carson's, Penny's and LL Bean, believe or not. Actully, LL Bean has the highest quality of these types of clothes, but they are also the most expensive.
The shirts are soft, comfy and breathe, even the long-sleeve ones. And to avoid jeans in 90 degree weather, I've found cargo type, or khaki type, or something nylonly (is that a word) but they are, like the shirt, designed for hot weather and provide the sun protection I need. Some even have swim linings in them so you can use them at the pool or on water rides.
I'll grant you that some of these clothes are not cheap, but when I can enjoy the summer weather and not get burns or rashes, I accept the cost. Sure is better than even 10 years ago when none of these sun-protection type clothes were even thought of.
And I don't care how I look, I'm protected from the sun and me and DW have a great time.
Dolby1000