I would have to say that it would be a good idea to make most of the default maps new with maybe 1 or 2 remakes. Some of the remakes from previous Halo games that I would LOVE to see are:
From Halo 2:
-Relic
-Terminal
-Gemini
-Colossus
-Burial Mounds
-Lockout
-Ascension
-Zanzibar
-Coagulation (Not Blood Gulch or Valhalla)
From Halo 3:
-Guardian
-Construct
-The Pit
-Citadel
-High Ground
-Standoff
I am fully aware that most of these will not be in Halo 4, but to see some of them return would be a HUGE plus to the game. Please feel free to post your favorite maps that you would like to return for Halo 4 below.