LBJ's ANC run sounds like it would do the trick and $427 to get to Plat isn't a bad deal if you plan on flying a lot next year.

The MIA run through SLC and ATL nets 5506 according to www.gcmap.com, so you'd be 2000 short, more or less. You could try to see whether you can combine that with a couple of quick turns LAX-SFO and/or LAX-LAS, each of which would get you 1000 miles for the R/T using the 500 mile minimum for elites per segment. The advantage there is that MIA can be done in a way that you get a day at the beach and either SFO or LAS can be fun day trips, as opposed to getting into and departing from ANC in the middle of the night. If cost is a factor, by all means do the ANC run, but I personally prefer to get something in the way of a trip if I have to do a run.

In the future, it is helpful in these threads to be as specific as possible about how many miles you will be short. "7500" is a bit too round of a number for me to feel confident in giving advice as to how about to cover the shortage.