I don't have gatecrashing, so I give about $28 - $68 for bridesmaid and groomsmen.. for bridesmaid and bestman will be $88, they have more things to do.
The diff for bridesmaids / groomsmen cuz some is just to walk the aisle only... there will be some helping with reception and other misc so give more lo..
PG, VG, MUA, hotel banquet managers all these... ~$68. i think it really depends on their service provided.. You can don't give if their service is not to your standard, =X
All in all, it really depends on your finances la.. you still need to factor in some other angbao u are gonna give for those they are driving, their petrol and parking. bla bla bla.. So, I would customize it.