How Much Should You Put In A Wedding Card? [LIST]

It's 2015 and things have changed, but have the 'rules of thumb' changed?

Is there really a right or wrong answer to this? Overall, it's what you feel most comfortable giving, but here are a few factors to consider.

1
Cover Your Plate
Rule of thumb is that you cover your plate. It's 2015 and the average cost of a plate at weddings now is $65. Is that too much per person? Too little? If you're going to a wedding that has a buffet, you still may want to give them a little more.
2
Distance
Unless the bride and groom are chipping in for your plane and hotel to their destination wedding, you could consider stuffing the card a little lighter. Or, perhaps, you could get something less-expensive off of their registry.
3
Wedding #?
If your best pal is getting married for the third time, it is totally acceptable to give him less than you normally would. After all, this is not his birthday.
5
Other Gifts
6
Attendance