Just to let you know..
I am a huge fan of Arrow and in no way do I find it a disapointment. The following recommendations are just suggestions that I would like to see. Therefore, it is my opinion and shouldn't be taken seriously. Saying that, I'd like to mention that although Arrow is amazing as it stands, I think it needs just a little traditional heroic tint.
I know it is supposed to be a realistic show and down to Earth, so no aliens, magic, etc. However, there's more to this suggestion. I believe only the persona "Clark Kent" should make a small cameo, and not the persona "Superman" or "Kal El". It would nice to see Clark Kent as a reporter of the Daily Planet interviewing Oliver Queen about anything, it could be before the introduction. By Clark Kent, I mean the mild mannered reporter with thick black glasses and a trench coat. It would just be a nice touch, no mention of him being a hero or him having to go do his duty, while a crisis occurs is necessary.
I know Batman or Bruce Wayne will most likely not appear on the series like in Smallville, but two other characters in the Batman mythos might be a more reasonable choice. Red Hood or Jason Todd and Bat Wing or Cassandra Kain. The reason I chose those two individuals was because they are both who have had a dark past or history. Red Hood could just be a simple crime lord or a vigilante [Like the gang, The Guardian Angels]; if chosen, I'd love it, if he was played by Jensen Ackles, since his portrayal as a voice actor. Cassandra Kain would be another vigilante, who could be effected by a certain drug. [Note: Justin Hartley's Green Arrow had a drug that was able to enhance certain features.]
The Smallville Episode "Beacon" had a scene where fans were able to upload clips of themselves defending Clark or the Blur. I hope the show Arrow does something similar to that.
How about you?
So I said a lot, how about you? What do you wish to see in the future episodes. Feel free to critique on my opinions as well. Add on or disagree, your choice.