Some thoughts...
-- SeaDek and similar products like it look fantastic, but they're more for pleasure cruising than working. You can get SeaDek in either glue-down or snap-in versions. Personally, I wouldn't pick this option though - too expensive and not really the right product for the job.
-- There's all types of marine anti-fatigue mats available (google for more info). Some with holes, some w/o. Very nice, heavy so they'll stay put easily.
-- Mats like you would see in a gym
-- "Home" versions of gym mats or anti-fatigue mats from HD or Lowes. These are typically 2' square pieces that click together. They do a "decent" job of staying together, but you may want to tape the seams or glue the seams. These will be much lighter in weight (and not as durable) as the better anti-fatigue mats mentioned, but less expensive.
-- Mcmaster-Carr is another great resource to check into regarding anti-fatigue mats. They should have lot's of this stuff to pick from.