It's semi formal but if you want to do a look that's inspired by the 1950's or space inspired (Doctor Who, Star Trek, Voltron, Sailor Moon, etc) then you're more than welcome to! But you can also stick with semi formal too. Whatever you're comfortable in that make you look and feel great!
If you're staying in a nearby hotel it should either be walkable or you can get an Uber/Lyft. But if you're driving then the venue has valet parking!