I'll echo that Green Lantern should be more about discovery and less about fighting supervillans. More Star Trek and a lot less Star Wars.

Hal Jordan should be out in the very farthest reaches of reality, meeting all sorts of strange creatures and visiting cultures/worlds. Hal works best as a cowboy. A lone ranger out in the darkness. He should rarely, if ever, come in contact with other humans- thus making his occasional returns to Earth even more jarring.

I think if Hal is a ranger, a rough and tumble cowboy, he should have a partner more versed in science mumbo jumbo. Maybe Hal is also into cartography and adding to his list of worlds he's been to.

As for the Justice League/superhero stuff, I'd give that to Jessica Cruz. I like her anxiety problems and it's nice to see a female GL. If I had to give it to someone else, I'd try and mix the best aspects of Guy, Kyle, and John into one character. 5 human GLs is overkill.