I love all of the restaurants everyone has suggested here; we've been to Citricos, Narcoossee, Geyser Point, Whispering Canyon, and Steakhouse 71 many times. However, if you're planning on leaving MK to go to a meal on the monorail, my recommendation is Steakhouse 71. We've been many times in park clothes and not felt self conscious at all. Meals are delish there and the CMs are great. You can either take the monorail, or it's the easiest/quickest walk from MK to the CR. GF is walkable too, but it's a longer walk.
Citricos and Narcoossee are a little more upscale, and when we've gone, we've always dressed up a notch from park clothes. I know it's not necessary; I'm sure lots of people go in park clothes without a problem, but that's just our personal mojo. Both restaurants are awesome...great food and great experiences with CMs. Whispering Canyon is fun and definitely a park attire kind of place, but the food is just "meh". Geyser Point is nice, but it would not be worth it to me to leave MK and take a boat ride to WL to eat there. We definitely enjoyed it when we stayed at WL, but we would never make an effort to go out of our way to eat there when not staying at WL.
I can't say anything about 1900 Park Fare, as we haven't eaten here. However, we have it booked on our late fall trip.
I hope you have a magical trip!
