Is it ok to do a table of blank place cards near the entrance of the reception hall and have guests write their own names then select their own table as they arrive? I don' t want to even try to tackle the whole assigned seating thing, but I thought place cards would still be nice so guests can claim a seat/table and not have to stand guard of it during cocktail hour.
People put down their stuff and that's it. I've never heard of what you propose and I'd think the bride was either an idiot or beyond clueless. Either do them yourself or don't do them at all. As long as there are seats for everyone, people won't steal seats. Someone is likely to be at the table to say that certain seats are taken.