The first question to ask yourself is "what is the largest piece of
timber " for each saw.

If you are regularly cutting 8 x 4 sheet stock your slab is a little
undersized, or you need very careful layout.

If you typically use smaller pieces it is plenty big enough.

I like mobile bases on equipment for two reasons. First is cleaning.
Second is to get extra clearance for odd large jobs.

Paper and pencil to layout floor plan. If the slab is in place some big
cardboard boxes to simulate equipment will be a big help.

Plan carefully for access doors. I rip 10' long stock by opening the
garage door.