I was lucky to be in Daytona for a business trip, 1 hour away, last month.
I scheduled an extra day for me. Just me. Family needed to stay home due to school, short notice of the trip, and also the cost of bringing everyone else.
My brother and his family happened to be there for their annual DVC trip.
I ended up spending about 1/2 the time with them.
Before meeting them, I was by myself for a few hours.
I really missed having my wife and kids there.
Then my brother and his wife and kids met me.
Once they were there, it was much easier doing things with or without them, just knowing I had family in the park.
You'll be fine.
The kids DO NOT know I spent a day at the MK.
I couldn't be down there, see all the stuff they'd like, and not get anything.
They know I went to Florida, and also know that Downtown Disney is a shopping area they visited, outside of the parks.
They also know I drove 'an hour away' from my hotel to go shopping for them.
So, the Walt Disney World stuff I brought home was well received, Space Mountain 3-D cups and Splash Mountain towels, stuff you can't get outside WDW other than Ebay.
Just be careful to not take any pictures of anything you didn't do with DD or see.
...
Years later..."and here's a picture of Mommy and Daddy at Blizzard Beach."
"Hey!!!!!!!"
Oh, one more thing...don't tell about the trip until DD is at least college age.
Better, wait to tell until she has kids of her own and can really understand, then pull out the pic of Blizzard Beach from when you were younger and let her figure it out.