I agree with hitnrun, just set up your market or limit hot keys for the routes which usually have enough liquidity (EDGX, BATS, NSDQ, etc). It depends on your style of trading and volume, so it may not make sense to keep track of all the routes available. I believe Sterling has a midpoint route, so that's one to check out. Hope that helps.
I´m starting to scalp (in a HFT way) with the highest volme as possible. That´s why I wanted to know all about my routes (what are the best rebate ones, the aggresive and quick ones, etc), so that way I could chose the optimal strategy to sending my orders. I just started with the hotkeys . Thanks