So having a single list of playlists seems a bit redundant to say the least especially when you have to scroll to see a playlist, that's not very good in terms of HCI, as you should always be able to see the playlists at first glance.
In my mind the way Halo 3/Reach separated the playlists into groupings makes the lists much more manageable and dynamic. Below are suggestions to playlist groupings with suggested defaults and maps for use.
CSR Playlist
FFA Standard - Mainly slayer with lower chance of objective types.
Team Slayer - Basic team slayer
Team Snipers - Team snipers
Team SWAT - Team SWAT (1 loadout only?)
MLG - TBA see my suggestions for playlists as a whole below. (Small maps + community maps)
Doubles - See below as well
All CSR playlists should playout as classic Halo games (same loadout at start, weapons on map, no abilities? no ordinance, reach kill limit not score)
Unranked
Slayer playlists
Infinity slayer
Big team infinity slayer
Multiteam
Unranked FFA (rumble pit)
Objective playlists
CTF
Oddball
Big team objective
Skirmish
Community
Griffball
Action sack
Flood
If you want to add any suggestions or questions please leave a response below.