I don't do it all the time, but I love fancy and will often find some ways to make even casual a bit fancy.
Sequined, beaded, rhinestone adorned dresses - Between myself, DD19, my mom and my grandmother, I have so many special memories involving sparkly dresses. While DD19 has stepped away from her sorority, I was so happy to see her prom gown get a few uses. Part of why we splurged on that gown was so that she had something suitable for formals. I'd borrow it for no good reason if she let me. It looks like stained glass flowers made of crystal beads and sequins.
Dinnerware - I don't get to do it often...primarily because putting the china cabinet back together is a chore, but I love to use the china, sterling, and crystal. It makes me feel like a queen in my own home.
Tiaras and Crowns - speaking of queens!!! I'm in the market for some new headgear. I used to have a few pretty pretty crowns and tiaras (for various reasons). Sometimes I'd just wear them around the house because you just feel a little extra special wearing a sparkly fancy headpiece. I bought a new one over the weekend but had to return it because it arrived broken. I'm doing a Divas race at the end of April and while they give everyone a tiara, I wanted something more unique. So, back to the drawing board.
Side gratitude to jewelry. I skipped it because it's more obvious, but the right mix can make me feel super fancy and special.