I rarely give suggestions to 3D modellers as I have apsolutely no knowledge on that, so please don't take this as me being a smartass or something..
Anyway, if possible please include multiple LOD's(even just one extra can dramatically improve performance), I don't know if many people realize that but that is the mother of good performance while maintaining awsome visuals, you may not notice it with a few planes but when things get busy you really notice the "kick" of high poly models with no multiple lod's and I see that quite a few modellers lately don't really care about multiple lods even some payware guys...
Anyway as I previously said, this is just a suggestion, I have no clue how much work is needed for that to be done...