I agree that the status is well worth it, especially if you can achieve whatever your airline calls its second level (usually 50,000 actual flight miles), which shouldn't be too hard given that your projected travel adds up to ~45,000 miles.

Granted, that will mean locking yourself into just one airline. But as another post pointed out, it also means the difference between 50,000 miles with 100% bonus vs. 40,000 with 25% bonus (or less, if the 40k is split among airlines you have no elite status on). That extra 50,000 miles, not to mention the potential upgrades on the domestic legs, are well worth the inconvenience of sticking with a single airline.

As for the comment that locking yourself in means you would miss out on special fare offers, I've found that most fares get matched pretty quickly, so even if another airline comes out with something attractive, just call your airline and you'll probably get a quote close enough to be worth it (and at 50,000 extra miles per year, that's worth upwards of $1,000 extra fares per year right there. I doubt you'd have to spend that much extra, though - I spend about $6,000 total per year for just over 100,000 flight miles).

As Punki put it in another thread, her husband used to fly cheapest and most direct. But a few upgraded flights with her made him see the light; he's already reached Premier Executive (50,000 miles) and is making noises about 1K status (100,000 miles). Of course, Punki can be a pretty persuasive gal...especially when she's right (as she definitely is here).

Good luck, and enjoy the perks!