I'd suggest a separate limited liability type entity for each group of sites or different types of businesses that you own. Then you have your personal assets, business A, business B, etc. If one entity gets sued the assets of the others are harder, though maybe not impossible, to get at.
The downside is each entity has to have its own bank account, charge cards, tax return, etc.
You can also set up your own retirement plan to save your money tax deferred. You can have one plan for multiple, closely held companies. There are also options beyond IRAs and 401K that a pension firm can help you set up.