GREAT idea for a thread, Amy!
My first trip was in 1980, and there was only the Magic Kingdom then. It was in January, and I remember it really well. Dad was an assistant principal at the time and had the chance to go to an administrators' conference in Ft. Lauderdale. He and Mom decided to bring my sister and me, and we rounded out the week with a stay at the Polynesian. GREAT family vacation, and in spite of my parents no longer being married I know we all think of that trip with fond memories. I remember the dumbest details... our hotel in Ft. Lauderdale was right on the beach, my sister wanted one of the coconuts from the pool bar but was too afraid to ask so I had to ask for her (I was in 6th grade, she was in 2nd, so it was an appropriate big sister thing to do). Our rental car was a Chevy Citation and when Dad and I went out to get food for my sister and me while parents went out for dinner, we got held up by the drawbridge.

The wallpaper in our room at the Polynesian was green foil wallpaper (ugh), and at the time 'Ohana was a fancy sit-down restaurant. The server brought us girls a flower and told us the correct side to wear it in our hair, based on whether we were single or taken.

Mom and Dad got some kind of fancy drinks in frosted tiki-style glasses, too. I wonder whatever happened to those glasses. I wish I had them!
The coupon books were still in use but Disney was transitioning to the one-price "passport." My junior passport was $15 for the day.

I only know that because I found it in some of my stuff and it had the price on it. Our first day we did all the "free" stuff, and my sister promptly got sick on the circlevision 360 theater that took you all over the US. So Mom took her back to the hotel room and Dad and I used some coupons that a friend had given him. I don't remember much more about the trip except LOVING the volcano pool and feeling really sad when we left. Here's a photo of me. No comment on my hair style or apparel. I was TWELVE.
I know that trip was something of a financial sacrifice for my parents, given that my Mom had only recently returned back to work after staying home with us kids for 12+ years, and that Dad had only been an administrator for 6 of those 12 years.
Our second trip was in 1983, just a day... we were visiting my grandparents in Ormond Beach, near Daytona, over our spring break, and decided to drive down to Orlando and do a day trip. Epcot was open, but since we only had one day we went to the MK. I don't remember as much about that trip, though.
I didn't return to WDW until 2001 when my girls were 7 and 3!

And the rest, well I'm pretty sure you know about the rest.
EDIT: My bad. My one-day passport was from 1983 and was $14. STILL.
