I got into this habit of cooking on some jerky racks that I bought from Cabela's I love them, because I can take them into my house, load the food up on them, and carry them out to the grill. Because I rarely ever place food on the actual grates in the grill, I don't typically care how dirty the cooking grates are. I'll use a grill brush on them to knock off any big crusty attachments... but outside of that , I don't clean my grills gates much at all.
Now, my jerky racks... if/when food sticks on them, they can be tricky to clean. I recently found a method that seemed to work well for me. I bought a couple heavy duty bus tubs, the ones I got are like 21x17", made by Tablecraft. My jerky racks easily fit in these tubs... some really hot tap water combined with Oxyclean in the tub with the jerky racks... 10 or 15 minutes of soaking, the gunk on the racks is easily brushed off with a stiff bristled cleaning brush. Since these Cablea's racks aren't stainless I do have a little concern with them rusting, so I stuck them in my oven after I rinsed them off... 150F for a hour or so and they were nice and dry. In the summer, I'd probably just stick them back in my pellet grill to dry off at 180F or so for a while.
Another option that can be obtained easier than those bus tubs, and can even be found large enough to hold a actual grill grates... a drywall mud tub... can be found at Lowes or Home Depot, etc...
All else fails, I do have a power washer...