Forum Moderators: LifeinAsia
Probably a group of Webmasters is not the best place to get tax and legal advice. I would recommend a competent CPA or tax attorney.
Any opinions you get here (including my own) are worth exactly what you pay for them...you wouldn't want to be quoting them in tax court.
DBA isn't necessary, however filing a trademark for each domain name will do exactly what you want. Check out the US Patent Office's website, they do federal trademarking as well (if you're in the US).
I don't really know where to start researching the options
My advice would be to buy several books on business structure and asset protection (the Nolo Press books are great), come up with a tentative plan for your sites and then run it by a state board certified lawyer who specializes in taxation issues.
There may be asset protection advantages to having multiple LLCs, but you have to weigh that against the costs associated with setting up and maintaining each LLC.
I would recommend a competent CPA or tax attorney.
I've had a lot of problems with incompetent tax attorneys. If I had to do things over I would have read several books on the subject before contacting a lawyer. Instead I read the books after I'd already shelled out a lot of money. If you read the books first it save time off off their hourly rate having to explain things to you and also helps you to identify the ones who know just enough to be dangerous but not enough to really protect your business.