Hi Wendy! Glad you've joined us - Welcome
It's not a bad idea to choose a separate host for each site - not only because of potential downtime, but also in the case that you choose to cross link your sites (if they are related). A heavy "link network" between sites hosted on the same server can be considered "spam" by the major search engines. If you dont plan to link between them in that way, it's not a concern.
I have all of my sites hosted at . They are not interlinked, except where it makes sense to do so (which is minimal) - and I like the convenience of having all of my features and all of my stats in one control panel. The support and service have been great this past year, and I am saving quite a bit of money having them all under the one account (24.95/mo which includes shopping cart w/affiliate program, affiliate program manager, etc as well).