ARGH the school schedules!!
First, don't decide anything based on K -- many schools start that with shorter days to get the kids adjusted. Look at the regular schedules for grades 1-5.
But, yes, you are going to have shorter days and really annoying half-days and in-service days. For this: before- and after-care can be awesome. We have a YMCA program that takes the kids to/from school in a little bus, and a church-based program next door that walks the kids over and back. We chose the latter, even though it isn't our church, and it has been *awesome*. Primary benefits:
1. They are open on all of the half-days and holidays and any weather delay as long as the teachers can get there.
2. They have an *awesome* outdoor playground and send the kids out to run around before and after school. Because our schools have shortened recess quite a bit since I was in school, this was a big, big deal for me. [I don't personally give much of a shit about "enrichment" -- in ES, my kids needed less butt-in-seat time and more running-around time]
3. They have an optional homework period -- they send around a note at the beginning of the year asking whether you want them to "encourage" your kid to sit and do homework. I always opted in, because it built the habit of getting the work done, and it freed up our evenings at home for relaxation and fun.
4. My kids made great friends with other kids whose parents had similar schedules to us. I have several friends there who now have been known to pick up my kid or vice-versa on a given day.
5. Many, many kids in the neighborhood have two working parents. As a result, the after-care is now the modern version of the "play with kids in the neighborhood after school." If my kids were home, they would have no one to play with.
6. My kids think this is totally normal. I realize that for others this may be a bug, not a feature. But kids are adaptable; they tend to do whatever you present to them as "normal," because they don't have any other frame of reference. As a result, my kids both had an awesome time in daycare and then in before- and after-care; in fact, my son gets annoyed when I pick him up too early, because, per 5, that's where his friends are!
As always, YMMV -- depends on your kids, your neighborhood, your options, etc.