One of the best parties I planned for a non-profit was a 1920's event. We had everyone dress in costume. The tables were decorated with money bags, paper money and fake gemstones.
For fun keepsake photos, there was a photo staging area with toy guns, hand cuffs, gangster hats and flapper beads.
During the middle of the event, we had gangsters bust in and demand the goodies from the guest tables.
Period parties are allot of fun. Hope this gets you going!