For your SIL, is she registered for fine china? If so, maybe you could get her a few place settings, or several serving dishes? I know that doesn't sound glamorous, but of all the gifts I received for my wedding, I do still remember who gave me each place setting, the gravy boat, the large platter, etc. It makes me smile ever time I set the table for a fancy dinner!
For your husband's friend... five boys! Wow. A good vacuum? (Just kidding, that probably wouldn't be a good idea...) If the family is local to the Bay Area, maybe a nice gift would be a family membership to the Monterey Bay Aquarium (ours was only $150ish for 2 adults and 3 kids), or some tickets to a 49ers game.