The trip you are picturing has your mother in the front seat, the kids in the back, a cooler in the trunk, and everybody happy at the first restaurant. The trip you may actually get has a step into the shower nobody mentioned, a hotel room at the far end of a parking lot, and a long wait for an elevator while the kids race ahead. You can tell the difference before you book, if you ask the right questions.
Local option: New Plan Care gives families in the St. Louis area in-home help so a parent can stay home: companionship, help with bathing and dressing, meals, and overnight care. Call (314) 405-0887.
Check the room in writing
Call or email the place and ask specific questions. Is the room on the ground floor, or is there an elevator? Is there a step or a tub edge in the bathroom? How far is the room from the parking spot you will actually use? Is the bed high or low? Write down the answers and keep the email. A vague yes from the front desk is not the same as a confirmed room that works for her.
Walk the route before the trip
If you can, walk the path from the car to the restaurant, the pool, and the breakfast room at her pace, not yours. Count the places she can sit down. Notice the curbs, the loose rugs, the long hallways with no benches. If she walks slowly, build that into the schedule. Plan two shorter outings, not one long one that ends with everyone irritated in the car.
Decide who covers home
Someone has to handle the house, the mail, the pets, and the plants while you are gone. Write that down with a name beside each job. If your mother needs someone with her during the afternoons you are away, look at what is available in your area, and ask each option what they will do and what they will not. A non-medical helper can keep her company, help with meals, and run errands. Her medicine stays with the family, her doctor, and her pharmacist, so make sure that part of the plan is clear before you leave. The Local Help in St. Louis page lists the kinds of help that are worth asking about.
Leave one afternoon open
Plan one stretch of the trip with nothing on it. That is the afternoon she naps, the kids swim, and you sit with a coffee and do not check the calendar. A trip with your mother and your kids can go wrong in the same ways a regular week does, so give it room. Most of the good moments happen in the open time anyway.