On our recent USA trip in Sept my wife & I flew first on Virgin America from LAX-JFK and, after various convoluted journeys, in first from SFO-LAX before our return on VA.
As we all know LAX is a horrible terminal but we did get priority boarding and were comfortably ensconsed in our roomy seats while everybody else filed on board. Plane is brand new, service was good and it was a pleasant way to spend 5 hours. We booked early and this sector was not cheap but it was a special trip so we splurged. Having said that it was the same price or cheaper than all other flights we could see in first/business on any other airlines for this route.
Next part of the journey was LGA-DEN & was on Continental/United. No Lounge, old plane, efficient crew but just went thru the motions.
Then from SFO you fly out of the brand new terminal which, in comparison to just about every other airport in the US is pretty amazing. Same priority boarding, new plane, good service. We booked these tix online about 4 months before flying and paid $US210 ea which in my opinion was a bargain.
So my take is that it all depends on where you're going as they still have a reasonably limited coverage. No lounges unless you want to pay in the terminals where they do exist. No particular benefits for Velocity member other than that I got a bunch of points for both legs. Much newer and better fitted out planes than any other US carrier. Good service with the usual Virgin twist - whether you like that or you don't. Pilot greeted us onboard and disembarking on both sectors. If you can score an upgrade it's worth it on a longer sector. Enjoy your flights!