Personally, I would be interested to play in any (but chess, for now) of the games I play regularly here in LG (OSKI, Shogi, 4iR, Gomoku, C6, SS, D&B, Breakthrough and EWN). Actually, I've been playing a few Amazons and DVONN lately but won't consider them regular games yet.
As for which game would be best suited for RTs, I believe that, ideally the game should have the following (in order of preference): a great number of active players; an active community (ideally with frequent forum activity). That being said and limiting myself to your games of preference, I'd recommend that you start a trial RT series in 4iR or Go.
If you would decide to start if go, then I'd say that you do so in 9x9, so that you can measure your results faster. I'd even consider taking part of that (although I really suck at go)
As for rating range within each group, I'd definitely go for 200 points. If you start with 4ir I'd start with the following groups: U1400, 1400-1599, 1600-1799, 1800-1999, 2000+. For Go, I don't remember how dans and kyus translate into rating.
Suppose you do start a trial RT series, I'd suggest: a- try to promote it as wide as you can; b- make it monthly or bi-monthly; c- don't start another game before the first cycle of the first game is finished (so that you have a minimum data); d- don't get happy with your results before you've seen, at least, 3 complete cycles, and e- don't get sad with your results before you've seen, at least, 6 complete cycles. Obs.: reduce the number of cicles in d and e to 2 and 4 if you devide to start with regular 19x19 board go.