We are hesitating between assigned and not. Every wedding I've ever been to has had assigned seating.
You could do a table plan (just print out on A3 paper perhaps tied in with your theme, then place it on a kind of easel just as you go into the function room where you'll have the meal) which provides a table number / name and lists the guests seated there. Then guests just have to find the right table!
If you have assigned seating at the table itself you could use placecards of some kind with people's names on. We're thinking about collecting pebbles from the beach and hand-painting peoples' names on each one to use as a placecard - plus they can take it home as a souvenir... it can be really nice if it's well done by someone with a steady hand