The original late 80'*, early 90'* Lexus LS series had yellow lights. To me it was quite ugly...but they were definitely yellow. Yellow light diffuses less in adverse weather conditions, but has less distance and contrast than standard or more white light.
I researched this EXACT topic ridiculously thoroughly about 2 months ago when deciding what lights to put in my car. I wasn't really looking for a specific "cool" look, but moreso I wanted to find out what type of light is best, as I was disappointed in the stock Bonne lights. I decided on the SilverStar ULTRAs (different from standard SilverStars) because the color temperature was around 4,000k...which is kind of in the sweet spot between yellow and true white/blue. This means I get excellent long range visibility and great contrast (makes things "pop" out ALOT more) and I don't get alot of diffusion in rain/snow because they're not so white/blue. I'm EXTREMELY happy with my choice and the difference really is night and day. If you have any specific questions, I can either answer them or point you in the right direction.
2001 Pontiac Bonneville SE - "SLE w/o the ugly" 3.05 gears, 180* thermostat, 35/20% tint, spoiler, leather, traction control, sunroof, leather shift/steering, automatic climate control. www.gillsystems.com