I'm not sure at what point superhero/comic book scores started getting samey and kinda dull. My money is on Graeme Revell's average effort for Daredevil, but I could be wrong. If you work forwards from Superman, there's little drop in quality until well into the 90's after Messrs Elfman and Goldenthal stopped scoring for caped (or otherwise attired) heroic types. Perhaps only the X-Men franchise has kept its musical head above water, quality wise, although from the solid and edifying heights of John Powell, it's slipped down to the knock off Remote Control meets Powell by Henry Jackman (not singling Jackman out on purpose, just wrong place, wrong time). Even Patrick Doyle turned in a fairly average effort for Thor; still, I suspect he got a decent paycheck and it's no bad thing keeping ones profile high.
Having delved into the back issues of FSM, I've been slightly surprised at how highly rated James Newton Howard is. It's not that I think Howard is a bad composer, on the contrary, his Shyamalan efforts are excellent to terrific, but the rest is rather variable. He certainly didn't do a great deal to perk up Christopher Nolan's morose Batman pictures while working with Hans Zimmer and with Green Lantern he gets a solo comic book gig. At least Green Lantern is materially more exciting than his Batmans (Batmen?), with a broad and very Goldsmithian, fifth based brass theme. Unfortunately, it doesn't appear particularly often and even when it does, it doesn't quite hit the nail on the head.
One of Green Lantern's biggest problems (other than looking like, coming across as and generally appearing to be a second to third rate superhero and artwork that looks like it's from a spoof of the genre) is that good ideas in its score are swamped with electronics. Sections sound like the horrible overlays that plagued parts of Michael Kamen's otherwise rather good original X-Men score. Not that Kamen was responsible for them, merely obliged to suffer having them put over his orchestral score, but it was clearly a sign of things to come. Of course, while Howard has put the electronics in himself, they smother some fine orchestral writing. Green Lantern isn't terrible but it doesn't really distinguish itself in the pantheon of superhero scores. Once upon a time, each superhero had his (or her) own sound world, now there's not a lot that sets them apart. Here's hoping Alan Silvestri can do something a bit more memorable with Captain America. As it were.
If you can't find a CD shop with your lantern (green or otherwise), go and acquire it from Amazon.