I met with my lawyer about this and here is what he told me. It is more important to look at who is doing the work on your properties than who owns them. He told me this: In general, people are going to go after the person that did the work because it's easier to prove them negligent. So, if you do all of your repairs yourself then the LLC doesn't provide you much protection because you (as an individual) can be sued for negligent work. However, if you hire out the work or have employees it is most likely that the company will be sued. In that case, the LLC does provide you with protection because only the company's assets can be taken away in a lawsuit and not personal assets.
There is an advantage to having an LLC to protect your personal assets in certain situations, but be aware that if you are doing repairs then you can also personally be sued, which will require an umbrella policy for protection. That's what I've been told... I, however, am not a lawyer and can't be 100% sure about any of the facts.
There are also reasons to have an LLC other than just protection. These have been talked about elsewhere, but it is important to consider them... taxes, anonymity, etc.