If you used the knot to track your guest list, you can use their seating chart tool. The wedding wire also has a good tool for seating charts. I think both you can import your guest list. When I built mine I started with immediate family and determined who would want to sit with who and went from there.
I did mine on poster board with post it notes. I drew circles for the tables & wrote ppl's initials on a post it. It worked well when last night we move around a ton of people. Start with groups of people that know each other. My family was easy since my mom, dad, and my mom's second husband (still consider him to be my stepdad), would not be sitting togther, but with their respective familes.
I made a diagram on the computer and printed a few copies. We grouped folks that knew each other and filled in the rest. I didn't necessarily make all the tables even either. I used pencil so I could write and erase as necessary. I also sat with both my mom and MIL to figure it out. It wasn't so bad.
I took all my escort cards, laid them all out on the floor and worked with them that way. First I separated people into groups (dad's family, mom's family, friends...), and then started trying to group them into tables. I found it really easy because that way I could visually see everyone, and just slide them about to different table groups.
Re: Seating Chart...