Great topic, Eagle, and it's made for some awfully interesting reads so far. But I believe we've all missed one important point that Doug has so eloquently articulated in the past: aviation is feast or famine.
Right now, since we are assuredly in a real famine here, of course it won't matter what airline we may aspire to work for or holding out for the right job offer. You'd have to be plain dumb or have some major source of funds to pass up on any offer from any operation 121 or 135 in such an employer's market.
But I know I'm not the only optimist among my fellow aviators, times will get better and we'll go back to feasting mode, and that point, I bet you'll start looking at the nitty gritty of contracts, terms and conditions, schedules and bases, times to upgrade and even family issues like school districts and spouse's preferences if you're married (man, I'm so glad that's not a factor for me yet, it'd be so tough to keep the wife happy and further my aviation career at the same time in an economy like this).
That being said, at a basic level of a professional pilot starting out, even in good times we'd be silly not to jump on the first good offer from a regional, for example, because of that almighty seniority number and the importance of jumping on that wagon ASAP.
For my part, I'm very ambitious, like my Aussie friend Snow, ever since my FSI days I've always aspired to fly internationally so my goal is to actually make it to one of the Middle East or East Asian carriers, Emirates would be number one then Cathay Pacific a close second.
The US carriers don't offer as much in terms of international flight, I mean, you'll spend years building up seniority and then you might get a route out to Heathrow or Orly or Schiphol, the usual. I'd like a shot at Singapore, Cape Town, Casablanca, Istanbul, Vienna and others. Very slim chance of ever getting a route flying to those cities for any US carrier, especially now with all these alliances. Just my .02