Fabbers, I need your help!

We just booked a family vacation for Florida for the end of March. We will be doing lots of activities - baseball game, Kennedy space centre, Disney (God help me), beach, and lots of driving in between.

I am stumped as to what to wear/buy. For the past 5 years we have done resort vacations, so I bring mostly swimsuits and cover ups.

With my weight gain, I don't think any of my summer wardrobe will fit yet. I need things that are comfortable (top priority!), Versatile, polished, work well with layers and not too constrictingg (especially waistbands - I have a sensitive tummy.)

Temp will be mid twenties (C). I wore fitted dresses and short shorts in my casual life most of last summer but I don't think those will work now with the weight gain.

Leggings will be too warm I think. Longer shorts look mumsy to me and are too constricting. Jeans are too hot and constricting.

Last year my unform for work was a silk shell and a flowy midi skirt wth a cashmere cardigan on top. Can I translate this into casual somehow? Casual midi skirts or dresses that I can layer over? Any other ideas? I need to start shopping stat!