Thanks for all the replies, we've changed the schedule and I guess I'll make my mind on last minute yet here are the two options I favour:

I might take the ferry from HKG airport to Shekou's port . Is it nice there?

And most importantly how to deal with a cab to go downtown?? My mandarin doesn't go much further than how much and the numbers... how much should I pay BTW to 999 serviced apartment in Lowu?

other option is waiting for my GF who's chinese but doesn't want to take the ferry and will reach HKG 5 hours later. in that case, is there an interesting place to visit around, except downtown HKG ?

Cheers
Luis