Various info to add:
First I would recommend getting an AMEX card that allows points to be used where YOU want them. IF you fly Delta quite a lot (like me) then you might want to get a Delta SkyMiles AMEX card. The bonus miles just for getting the card can be pretty sweet depending on which card you get. Travel advisers DO NOT RECOMMEND getting a card that ties you to one airline.
Of course actually USING those miles is another trick. You need to book as soon as possible (I believe the earliest is 331 days out). Be flexible. Early or late flights are easier to find. Avoid holidays and try to fly during the week.
On my recent Medellin trip I had to catch a 6AM flight on American. My return got in at midnight (actually 1AM due to a storm in MIA). I booked it 5 months in advance and that was still the best I could due over 4th of July.
Delta and American both have calendars that will allow you to see exactly what's available. Be careful though because they might give you a 30,000 mile "deal" but it could include a side trip from ATL to Newark or even an overnight connection.
I have also noticed on American there have been times when the best economy seat was 70,000 miles but Business Class was available for 60,000.
Both will offer to sell you miles. If you hold at least a GOLD Delta SkyMiles AMEX card you can use their "Pay for Miles" program that will allow you to combine miles and cash.
http://www.lowcards.com/
https://web.da-us.citibank.com/cgi-bin/ ... antageCard
https://www124.americanexpress.com/cards/delta/
Citibank AAvantage Mastercard and their new AMEX card allows you to use miles at reduced amounts. These are listed by quarter.
https://www.citicards.com/cards/wv/copy ... eenID=1213
Regarding AMEX themselves, I have had at least 4 charges I've had to dispute over the years and all 4 were found in my favor. I made the call, got a note in the mail and that was the end of them.
As for rental car coverage, yes, an AMEX card will cover SOME of your damage but I believe it may be AFTER your personal insurance kicks in. For $19.95 per rental AMEX will cover everything. That is probably not that could of a deal if you rent more than 4 or 5 times a year but it is something to look into.