Some people rave about the Mav remote Thermo, but I have had zero luck with those. It does not like the double paned windows and is always hunting for a signal and beeping when it can't find it.
To tell the grate temp, I use a Polder type Thermo I got from Costco Business for 14 bucks or so. It is the type that you would put in the meat to know the internal temp. Well, I wad up some Alum foil run the prob through the foil and set on the grate. The Alum foil keeps the probe off the grates and tells me the temps at grate level.