A fever of 100: just my opinion~ no preschool today (and sounds like you are keeping him home)... with a low fever like this and seeing that he's got energy, I'd suggest walk around the neighborhood if you can (or a park that isn't too frequented, so as not to spread germs). I personally wouldn't take my son out when he's like this unless it was to run errands with him in the stroller... being outside is great for getting better. My usual concern is always making sure that his cold/virus germs are not going to get other people sick. Plus, with the stroller, if he does get tired, he doesn't have to walk.
Take tissues (if needed) and hand sanitizer too, as well as water, and be sure to find time in the afternoon to snuggle up on the couch with some books. If it were me, I'd make dinner early, but that's because my son if far more needy when sick by dinnertime. Just my two cents....