"It sounds to me like my original plan to get some additional DNA kits for other family members is pretty much useless. "
Again, it depends on your goals. If you have living family members who are of older generations than yours (parents, grandparents, etc.), then you absolutely should test them - the further back the better. It doesn't have to be "direct" ancestors either, great uncles would provide more info on their specific line than you or your parents. The reason is the DNA gets diluted each generation, so there could be matching segments that are no longer there by the time they got to you.
As far as which company, that's your call based information here and elsewhere. Here is a summary:http://www.isogg.org/wiki/Autosomal_DNA_testing_comparison_c...