What playability do steep cards have without the use of minis...other than a short straight?

"steep" cards are really more like "hard" manuvers. These are harder turns and climb/dive that the planes can do.

If you had none of those, then it's be pointless to have differnt planes as they'd all pretty much act the same.

Thanks! I'll be checking out some other manuever decks.

Four Eyed Warrior said:

Well, _Burning Drachens_ has number tokens for indicating altitude:

http://boardgamegeek.com/image/158642

so it plays much the same as with minis.

if you don't have Burnin' Drachens, you also may take dice or coins to indicate altidude - works as well.