I loved every single one of Halo 2's BTB maps; while a map like Containment isn't on the level of Terminal, Coagulation, or Headlong, it still was a good match to be used for straight objectives like Neutral Bomb, Multi-Bomb, and Multi-CTF. Plus great games from Waterworks, Relic, and rarity 1-CTF/1-Bomb matches in Zanzibar and Burial Mounds. Avalanche and Valhalla were two solid maps, but had their issues with me. Really disliked Avalanche's mid-section; felt too forced and the Shotgun room promoted camping. Valhalla being crunched made spawn killing and controlling the hill easy, thus controlling the game, notably in Slayer.
Certain of those maps can be re-created in some form. Disabling Jetpacks and you can roll with the other three AA's and not a big change will occur for the maps. I would just love a map redesigned similarly to Terminal and another for Coagulation.