This was something I was worried about, especially in Halo 3 which shipped with Maulers strewn over all the maps. I hope they include both versions of the maps that were Bungie-forged (e.g., Snowbound and Boundless, Epitaph and Epilogue, Sandtrap w/ and w/o Elephants).

I am also kind of hoping they give us a few more options for Halo 2 maps. Some had some issues with weapon layouts, like Sanctuary (the No Duals vs. Human Only argument). It would be nice to have a "No Plasma Pistols" option to avoid the PP+BR combo that caused a lot of problems.