I don't know what kind of work space you have available, but I keep my welding and grinding area on the opposite end of the shop from my work bench. Welding slag and grinding debris ends up on everything and that's the last thing you want in your assembly area. Something to consider.
My work bench is 4x6 and 1/2" thick. My welding table is undersized at 2x7, 1/8" thick, but I use heavy steel saw horses for anything too big for the table.