All your domestic routes are on the "easy" side of upgrade with the exception of IAH, of course. Anecdotal evidence here on Flyer Talk seems to indicate that most plats based at EWR are having a tough time with upgrades, but a lot depends on the routes you fly; these really shouldn't be too bad.

It's a bit of a toss-up really. Personally, I'm philosophically opposed to mileage runs, especially one as costly as this one.

As a plat you'll get a better shot at upgrades and a better mileage bonus...that's really about it.

But as a rule plat is better than gold, no question about it.