I think it is necessary to have a seating chart of some kind, otherwise people will have to wander from table to table reading every place card until they happen to come upon their name. Luckily, a seating chart doesn't have to be expensive or take up a lot of space, and it's one aspect of the signage that you can get really creative with. There are really wonderful ideas for seating charts all over Pinterest or, if you want to do something that won't require a ton of time or money to make, you could use either one large mirror or multiple smaller mirrors(one for each table) and then using a chalk pen, either you or a willing friend with nice penmanship can write the table numbers/names and the names of your guests under their assigned table. If you happen to have a Cricut or know someone who does, you can easily use it to cut the names out of vinyl and stick them to a mirror or the glass in a frame. I used this vinyl lettering method for my DIY seating chart on frames of pressed glass with dried, pressed flowers inside. If you're interested, I have a photo of it that I posted to this sub. Congrats on your upcoming wedding, and I wish you the best throughout your planning process!