Wow some great advice in this thread.
I wish I could have read this a year ago, I tried to make too many sites at one time and realized to be successful I would need a staff to help me. Just to manage the domains alone takes time, and if your doing this as a second job...you need to be building pages in my opinion.
I also think one monster website with a ton of traffic is best, of course you would need great content...this is the number one thing...content. You can have a zillion domains with one page...but once the surfer realizes nothing is there...he will not be visiting again.
At least the white labels keep the visitor interested...so this works until you decide to develope the domain. Also blog feeds...since you don't need to spend time updating.