I have a self healing Omnigrid that I "refresh" every now and then by laying it on the dining table, laying soaked wet towels on top and then I lay a plastic sheet over the towels and place books on top of those for weight. I'll leave like that for a few hours. Oh ... before I wet it down I 'scrape' the surface of it with the edge of my 4.5 square ruler. I may also do this after the "refresh".
I also have a non-healing HUGE Beba mat that more than covers my 35 x 60 table. I've been using this mat exclusively since May, but I recently got (from a member of QB) an 18" Olfa rotary mat which I love for it's turning ability. No more picking up and carefully replacing pieces.