Wow! Do you arealy take enough supplies to do all three (sew, quilt and emborider) at one retreat? That would overwelm me. I quilt on my LA so that isn't going anywhere, and my embroidery machine is quite large so I'm not tempted to take it anywere unless I am taking a class on how to use it specifically.
To your table question, I really liked the folding table I had for my Viking that was bought 30 years ago. It got hauled around and set up and down for many, many years. I tossed it after the veneer was getting so bad that it was snagging fabric (after taping it up for several years when it wasn't so bad). I took off the hardware and had plans of having DH make me another top for it.
I liked that the legs splayed out instead of being vertical, that really helped cut down on vibrations. Even if they still make them, I'd not want to "recomend" as I have no idea if new ones are anything like the old one - but if I was in the market, I'd be looking for that type of leg configuration.
I like using cases on wheels. That way nothing can come out. However it would also be easy to make a couple of cases that fit inside the wagon, so you can load them up and only have one or two "items" to haul in and out. I love making big bags with lots of compartments to put stuff in.