Maurice Chavez from VCPR would be good, in my opinion he was even funnier than Lazlow and if the two of them had a confrontation on Chatterbox it'd be awesome.
Also, on www.gtagaming.com they've confirmed that Avery Carrington and Donald Love are back and I'll tell you lot an idea I threw down in the forums over there, I reckon you'll have to kill Avery in GTA:LCS for Donald Love, maybe because;
1. How Avery treated Love in Vice City
2. Carrignton is getting in the way of a big deal
In any case, it'll be good to see both Love and Avery back in the fold don't you think?