The idea I was running with there was A) Inexpensive to keep prices down, and B) Keeping things in the "Special Action Figure" packaging because it's Vinty and appealing (at least I feel it's appealing looking) and should be cheaper than most other types of packaging.
With that in mind I think hoping for new is kind of out there... Or at least all new anyway.
I also think 2 of the same guy may limit desirability... That's why I lean a little more towards a Fleet Trooper/Stormtrooper type set. Have the background set up as the Tantive IV hallway.

Or a TIE Pilot/X-Wing Pilot... Have the background be space and their ships in the distance behind them or something.
Some sets I'd dig then, with that in mind:
-Fleet Trooper/Stormtrooper... I like that idea, and I could use more of both. While I'd like more RFT's especially, I like the idea of it being a set of two desirable figures. Especially if it's a really good Stormtrooper... The RFT has to have a new head though, and a belt with a working holster.
-Hoth Rebel/Echo Base Rebel... Less of the "Versus" theme there, but again new heads and hats would be welcome.
-Snowtrooper/Snowtrooper Officer... I like this as a method of getting out a Snowtrooper officer with minimal new tooling.
The other possibility is mixing the Snowtrooper Officer in with an Echo Base Rebel and mixing the Snowtrooper in with the Rebel Trooper to keep the "Versus" theme going.
-Biker Scout/Endor Rebel Trooper... Make an Endor Trooper variation, however you want to go with it (softgoods vested one on the current figure's sculpt would be swell though), and the new Speederbike Scout... I'm in for a lot of this set.
-Endor Trooper Variant 2/Endor Death Star Trooper (jumpsuited guys)... The latter could simply be a variation of the AT-ST Driver sculpt with a new head/hat, or whatever. The former could be perhaps a little extra new tooling than normal but still re-using legs/gear easily enough.
-Yavin Hangar Technician/Pilot... Again, maybe slip a couple extra X or Y-Wing pilots from Yavin in, and get the Hangar Tech out too with those slick little light sticks perhaps?
-Cantina Monsters Set 1... I'd like to see two done like this, as exclusives, which would be modern sculpts of the classic outfits. First would be Greedo & Red Snaggletooth... Modernized sculpts of the classic jumpsuits, boots, colors, etc.
-Cantina Monsters Set 2... Same as above but Hammerhead and Walrus Man.
If these were really creative, you buy both and you build a Blue Snaggletooth with parts included in both. As an exclusive I'd pay a higher price for it. I'd pay $20 a piece for these if done right, as an ultimate fan-wank.
-Jabba Goons #1... Simple re-release of the Gammie Guard and a retool of Kithaba from this year to make a better version of the other Klaatooinian guard from POTF2... Give him a removable girlie backpack, new paintjob... I'd be into this bigtime.
-Jabba Goons #2... Kitbash one of the unmade Weequay Guards. Kitbash Yoxgit or perhaps a new head to make a new 8D8 using the BGJ38?
I'd be into other sets too, even with main characters, but the idea I think would have to stay somewhat the same, minimal new toolings and such, for the price to really stay where it is. A single figure is $10, so $15 for 2 you really need to keep things realistic with this I feel.