Have you seen these yummy looking salads over on Pinterest? They are in Mason jars and you can make them up ahead of time and they keep good (not soggy) for up to 4 days! Genius!! 
So, I gave it a try, and it works fabulous! Give this a try! Add you dressing to the bottom of the jar. This is a Olive Oil Balsamic Vinaigrette, super yummy!
Then add your vegies.
I add my vegies in this order
Onions
Mushrooms
Tomatoes
Cucumbers
Spinach
When you are ready to eat, just shake it up and eat. The trick is keeping the dressing away from the spinach so it doesn't get soggy.
So easy and yummy!!
What size jars did you use?
probably the large jsr depending on tge size salad, right!!!