I thought this part was going to be super hard - 2 sets of divorced parents (and both dads have dates) who don't want to sit together, a few of FI's friends in a major feud (involving the best man and a groomsman, with some of their friends taking sides)...
Main things:
Sweetheart table for us
Moms/Siblings table
Dads/Stepfamily table
Uncles/Aunts (2 tables)
Bridal party - for the remaining 7 tables, all friends, I put 1 or two members of our 10 member bridal party (with their dates) at each table, so the bridesmaid or groomsman can act as a "host" to the other guests. I put our NYC friends at one table (they all don't know each other, but should meet), and grouped everyone else by logical social circles (and luckily, the feuding groomsmen had enough mutual friends on each side that they're separate). I am so pleased with how this turned out.
WHEW! That was one of my last big checks to do! Now I just have to make their place cards and a few smaller things...