I don't usually watch morning TV, so it was really a fluke that I saw the RP ad this morning on WMUR.
When I watch TV (not that often), Romney seems to be running the most ads; seems like I see at least 1/hr whenever I watch.
I see a fair number of McCain, Obama, and Hillary ads.
I haven't seen any Rudy or Thompson ads yet.
I occasionally see a Richardson ad. Some months ago, I saw Dodd ads in the very late night / early morning hours.
I usually watch or tape Nightline, which airs at 11:30 pm here. Almost every evening there are Romney, McCain, Hillary, and Obama ads which run during and after it.