Me personally, I would wait and gauge the crowds once I arrive, then decide if Quick Queue is worth it for your family. If you have no interest in the larger rides (the coasters Manta and Kraken, the flume ride Journey to Atlantis, Turtle Trek, Antarctica, the SkyTower and Wild Arctic) then its not needed at all, as the rides in Shamu's Happy Harbor don't offer QQ access. I'm not sure how old your kids are so I can't guess what level of rides they might be interested in. If you arrive at rope drop, you may well be able to get the bigger rides all done at park opening with minimal waits and be able to save the cost of Quick Queue. We always buy it, but I also have two fellows who LOVE the big rides.....so its worth it for them to be able to re-ride the coasters all day long without making me wait forever for them!!
While reserved seating is a nice upgrade, its something I don't think is necessary ever (unless maybe during the two weeks of Christmas Break and the 4th of July). We have had it once, and while it was nice......the money you spend on this feature could be used better elsewhere in the park (YMMV). As a general rule, just plan to get to the shows 20-30 minutes ahead of time and you will get a perfectly acceptable seat.