Hi Walter,
Thanks for visiting the Disney Parks Moms Panel with your question! A getaway weekend with your sister, what fun!
April is such a lovely time of year to visit Walt Disney World. Spring is in the air. I definitely recommend that you visit the
Epcot International Flower and Garden Festival while you are there. At this festival, you can see beautiful topiaries and learn about gardening and flowers. This year there are Garden Marketplaces where you can sample wonderful, fresh food. You do need theme park admission for this festival; however most festival activities are included with theme park admission.
I would also suggest that you and your sister spend some time at the Downtown Disney and BoardWalk areas. These areas have fun and somewhat different activities that you can do. At Downtown Disney, you might consider taking a flight on
Characters in Flight. This huge, tethered hot air balloon rises 400 feet into the sky for an amazing view. For an extra-special view, try it at night! At
Disney's BoardWalk, you can take in amazing entertainment in the open air, or rent a surrey bike and pedal around Crescent Lake.
I hope that this gives you some interesting ideas for your visit with your sister, Walter. Have a wonderful time, and please do not hesitate to come back and ask if you have any further questions!