Well...as you probably know a Trine is a positive flow of harmonious energy. A Grand Trine is a closed circuit of this harmoniously flowing energy. If you jump into that stream then you can use this energy. Sometimes Grand Trines don't get used alot or aren't very productive because people take them for granted. It's too easy.
The fact that you have a Grand Trine in Air signs involving your Venus' and Mars' is quite something! Off the bat I'd say that there is a helluva lot of sexual energy between the two of you! Do you ever get out of bed? ha.
But, actually, together you can probably accomplish quite a bit - because you can get (mars) what you desire (venus) together. It means there is a strong desire nature between the two of you (could be a desire for Home - 4th house - or sex or things. Because it's all happening in Air signs I'd say that you guys have IDEAS! Now the trick is to bring those Ideas down to earth...make them happen. Manifest them. If you have some dynamic opposition (kite?) happening within this Grand Trine then that might be just the 'challenge' that you need to manifest those ideas. Cerebral.