Assigned seating seems to be the norm - it's all over the Knot. But I'm from a rural central Indiana town and I have NEVER been to a wedding where seating was assigned. Granted most people I know don't spend a fortune on their weddings, but all the weddings I've been to guests seated themselves wherever they wanted and most were buffet style dinners being served.
If you do a seating arrangement, how do you account for last minute changes to the guest list? What if someone brings their significant other assuming they were allowed a +1, that you didn't account for?
I would like to at least reserve a couple tables designated for immediate family up front. What do you think about making general table assignments, ex. Reserved for the Smiths, College Friends, etc. with a little more thought put into phrasing, but you get the idea.