It depends upon what projects you plan to make using their equipment. They do have a vacuum former and their ShopBot CNC machine will take a full 8'x4'sheet of plywood or MDF.
Their basic wood working SBU covers things AR already has. Plus, it doesn't cover all of the equipment in their Woodshop. The basic metalworking SBU may grant you access to more tools that we don't have at AR. They have a welding area and classes for welding, but if you already know how to weld that won't be of much use. Then their are their lathes and machining tools which would be handy to learn how to use. They have a textiles area as well.
Lots of choices. I've found that the classes don't teach much skills, but rather that you know the basic safety of using those tools and know the specific rules & layout of their shop areas for use of their tools and things like dust collection, etc.
Think about what projects you will want to make, check off anything you can build or do at Arch Reactor, then choose the SBUs for the tools you want to use most.