I really feel lucky after reading some of these posts. Here in Seattle I use Alaska Airlines a lot. With American being a partner I was able to book the round trip Seattle to MIA with miles for two of us without any problems for dates and seats. The MIA to SXM was a separate ticket. Trust me, this is great coming from the West Coast which is a hassle every year as you can't get to SXM in one day but you can get home in one day due to time change.