Anybody have recommendations for a pair of tights for summmer riding that are a light and cool as possible, while keeping the sun off? All the adverts for tights talk about how warm they are... not excactly what I am looking for :( I prefer to use clothing rather than sunscreen to block the UV.

try Pearl Izumi Tokyo Tights. They are the weight of a lycra jersey and I wear them here in Mexico to turn back the sun. I have used them in mid-80's and to ME they are comfortable. YMMV of course. Check out Altrec.com in the running pants section.

Those sound somewhat like the kind of tights I am looking for, but I am looking for cycling tights (with the pad), and kind of like them to fit tight to keep them out of the gears. I guess if I can't find that, I can just wear cycling shorts that have the pad, and some light weight tights over them. But I would prefer to keep the layering down to one layer.

I don't like tight tights, especially in hot weather. I got a pair of Rivendell's MUSA pants for Christmas, and after I got done pretending to be grateful, I actually rode in them and like them a lot. Also available in shorts and knickers. Wear 'em with Andiamos or just over ordinary shorts. http://www.rivbike.com/products/list/30?page=3

try Pearl Izumi Tokyo Tights. They are the weight of a lycra jersey and I wear them here in Mexico to turn back the sun. I have used them in mid-80's and to ME they are comfortable. YMMV of course. Check out Altrec.com in the running pants section.
The Pearl Izumi Tokyo's are tight enough so they will not get in the chain, but looser than skintight. I wear them over padded shorts, it works great.

I just use bike shorts and a jersey when I ride no matter how hot it gets. I mean, most good cycling shorts are nice enough not to be warm or hot and unless you're wearing thermal wear for cold weather, it shouldn't be a problem.

Though, you would get a dark tan on your arms if that matters. If it does, well, I use sunscreen though it didn't really work in preventing me from getting darker. I see some guys who use arm warmers to keep the sun out but it's plain nuts IMHO since it makes you hotter.