I do not know how ctf is at cs source. but jCTF at cs16 was also a lot of fun. So I think they should be added:
1. Remove flag defuse time. (I changed it at my sw)
2. HP regenation area around flags. (I added with some plugins)
3. Drop weapons and Duration of weapon remove. (I tried to do it, but the timers confused my head. I wanted it to be smooth but I did not succeed so I did not go on.) (It's hard to write a plugin.)
4. Shop must be added and Xp for flag-hitting players, kill bonus. for Invisibility, extra speed, awp, grenades, like. (I wanted to write a plugin for it, but there were many shortcomings and I did not have time) {CaptureTheFlag_OnFlagTaken , CaptureTheFlag_OnFlagScore )
5. (maybe) Drop health pack or somethish after a player dies.
6. (maybe) when a player capture a flag change him player model.
7. unlimited magazine (ammo)