If you want to refresh your co-star/film memory: http://www.dorisday.net/Film_List/film_list.html
Top 5 Doris Day Leading Men:

James Cagney
Rock Hudson (& Tony Randall as part of a team)
James Garner
David Niven
Stephen Boyd
Bottom 5 Doris Day Leading Men:

Richard Harris
Peter Graves
Robert Morse
Richard Widmark
Ray Bolger