Generally, I'll wear running shorts as long as temperatures stay in the 50's, though I'll often go to a long-sleeve technical t-shirt as it gets into the lower 50's, especially if it's breezy. I'll switch to running tights only if the temps get down into the 40's, which isn't that often where I live. I never wore anything under them.
If showing off is your thing, nothing beats the silky, shiny, thin, stretchy, nylon-lycra blend tights that were popular for a lot of years. Nike made my favorite ones, though Reebok, Dolfin, and Brooks all made similar ones that looked, fit, felt, and performed great. I still keep a few pairs around. They are getting harder to find, and you often have to go to runners specialty places like Road Runner Sports or Insport to find them. Typically, they're only available in black, navy blue, and MAYBE royal blue these days. Not like the 80's and 90's when they came in many colors and patterns.
The other thing that's happened is that most of the running tights now are made of polyester/lycra blend fabrics. They tend to perform somewhat better and are more durable, but they aren't as stretchy, and have a matte finish (not shiny), so if really hanging it out there and showing off is your thing, I don't think they'd be quite as good. Also, it's pretty much down to black and dark blue for colors, though Adidas notably makes theirs available in white, to wit:
White Adidas Techfit Running Tight - XTube Porn Video - Soccer1980
The polyester/lycra tights are usually quite a bit more expensive, too, unfortunately. It's getting hard to find a pair for less than $40, and they often run $60 to $80 for a nice pair. You used to be able to get a pair of nylon/lycra running tights for $15 or so at Big 5 Sporting goods, and even a nice pair rarely topped $25. The nylon/lycra tights weren't that durable, though, especially the cheaper ones.
. The brand I like so far is "Road Runner Sports" but I am sure there are many more out there.
