I don't know of a site that lists standards for all the states, but the following site should tell you what you need to know regarding your state:
http://www.firn.edu/doe/curric/prek12/frame2.htm
As for "traditional" vs year-round, year-round is better imho because:
1) You can do less per day
2) You get more done per year
3) There isn't a large gap of time during which you conveniently forget everything you learned the year before
Of course, you might take out a few weeks for special things like vacation or visiting a relative or attending a homeschool convention, and any outside classes will still follow a semester schedule, but overall you'll just spread things out more. The amount of homework each child has to complete per day, even in the later grades, shouldn't require more than 2-3 hours, leaving most of the day free for fun things and extracurriculars.