My advice- Think long and hard before flying for a living. The guys warning you and trying to dissuade you are all airline guys. Most of them were not that different from you. They all wanted to be pilots living the dream. They are here, and have nothing to gain by warning you off. Consider the source when listening to your flight instructor friends. They have not flown 121. Realize that you are not going to be the same person 10 years down the road. Seeing the world and nailing FA's today, somehow morphs into being stuck in a $hitty hotel alone on Christmas in the midwest tomorrow. Phone calls to your friends about the crazy overnights turn into phone calls to your lonely wife and a 3 year old child you hardly know.
If you fail to heed these warnings, you have no one to blame but yourself. You have been warned.
You have some valid points, and I definitely see how things could get tough living that "A-life" (A for airline, like G for gangsta). The question I ask myself when I hear people talk about "living the dream" is what they actually consider the "dream" to be. If your expectation (like certain CFIs I know) is that you will be working very little and partying like rock stars, then yeah, I see how that could get old really quick if it actually ever does happen for one thing, and become extremely disenchanting if it doesn't. If your expectation is that you will have the opportunity each day to make a living by getting up and becoming better and more skilled at something that you love, then there will be plenty of opportunities for that. That's probably way too optimistic for flightinfo, but believe me, that mindset has kept me from burning out on instructing after many hundreds of hours of bad landings and near death experiences.
Now, being 30, I actually probably will be the same person in ten years. Hopefully, anyway. I like who I am... but I will continue to try to improve myself.
I guess the point that I'm trying to make is that people, I think, are always trying to "arrive" in life, so they can "relax." My contention is that you never "arrive," and life is such that it never allows you to "relax." Anyone who tells you differently is selling something. But there is still much joy to be had. Life is about the journey; being on the journey is "arriving." It's an uncommon mindset to be sure, and definitely awkward for some. (Ahh, that sweet mountain bike racer ethos showing through once again. It has served me well.)
Using that logic, I have decided that working in a 121 environment would be extremely beneficial to me and my career progression (the flying and learning part, not the rock star part.) However, I am not placing all my hopes in an airline to satisfy every desire that I have in life. It's not a panacea, and to expect it to be so would be foolish. I have the responsibility of making something of myself, of making myself happy; it takes more than just accepting the job offer and waiting for the upgrade.
Being away for Christmas would be disappointing, but it is just a day, afterall (as religious as I am). What's wrong with the other 364 to spend time with your family members? (as well as the other 364 to live your religion?) I mean sure, spending time with the extended family is good and should be done, but I think my most pressing concern would be for my immediate family. To be sure, being physically gone would be a challenge, but I don't think that people who are struggling in their relationships take good enough advantage of the time that they actually have to spend together. They are in this "gone all the time" mindset, so they overlook real opportunities to help solidify and strengthen the relationship.
But then again, I am still young, single, and quite inexperienced with the ways of the world. That's just what it looks like from the outside looking in.
Anyway, I've been warned.
-Goose