Robo - I'd say Queen were bigger in the 80s at least in album AND singles sales - with albums like Greatest Hits, The Works and A Kind Of Magic. As they started selling more in Europe and the rest of the world their success in America started going downhill rapidly after 1981.
Queen's success in the UK at least spreads throughout the 70s, 80s and into the 90s due to Freddie's death. They are the 2nd biggest selling band of all time in the UK after The Beatles (of course).
Dire Straits really were an albums act - massive in the 80s and then I think after 1991 (?) they virtually disbanded.