DH and I do love going to the movies. I appreciate the full artistic effort of the production by seeing it on a big screen, with the right sound system. Clutching arms, holding hands, elbow nudges at the good bits, sharing a good laugh.
It's fun to be absorbed in the experience of watching a good story unfold. I'm happy to bring "the willing suspension of disbelief" (i even liked John Carter of Mars ).
I just wear whatever I normally wear on a weekend, not a big deal. We're sitting in the dark, so who cares. Ps, if you live in a chilly climate, don't wrap up too much in the theater, you'll be that much colder when you get outside again,and you won't have anything else to layer on. Learned this from personal experience from living on the East Coast. I'd guess the theater will be fairly crowded, so the body heat of everyone will warm the place up.