I don't know how Bill lucked out in February, but I've been to RR several times in mid-March and have always been cold. It is a good 20 degrees colder in, say, Black Velvet Canyon than it is in Vegas, and if you are in the shade with the wind gusting to 30 mph, you can definitely get hypothermic if dressed for town. I've worn powerstretch long underware on almost every shady climb I've done in March, and on one or two sunny ones as well, and I have only felt a little too warm for a total of several minutes on sunny stances when the wind died down.
As for crowds, they really are totally avoidable, especially if, as Frank describes, you come equipped with a backup plan. On the multistar classics in Black Velvet, you may have to share with another party or two, but not necessarily. In Oak Creek and Pine Creek Canyons, you may need a backup plan for your backup plan. If R-rated routes are ok, there's quite a drop-off in traffic on them, and cloudy weather with some wind cuts the population way down on the longer routes.
I've also found that an early start works really well for the shorter popular routes. Folks who want to do Birdland or Dark Shadows tend not to be lining up at the gate at 6 AM; you can be up and down before the lazy bums show up to clog the route. Same for Frogland---you'll likely be first if you hit the BV parking area at 6 AM. Easterners out for a short trip can easily play the early game: just don't go off Eastern Standard or Daylight time, and even a 4 in the morning alarm is just 7 AM wake-up for your body clock.
Early starts don't necessarily work for Crimson and Epinepherine, for those a lot of folks are thinking crack of dawn...