Being a petroleum field engineer is what I've been doing for the past 3 1/2 years. I work for a leading European company in this field and there's nothing I'd rather do more (job-wise...).
Being a field engineer means I move around more, I interact with a lot more people than I would, say, in an office. This is the fun part, seeing places, working on impressive projects and just seing things "move". If I were to be a regular "suit" engineer, as we call them, I wouldn't see 1/10th of what I get to see like this. Plus, you command a lot more respect in the field, where not everybody and their cousin is an engineer.
Of course, this also means working long hours and enduring tiresome trips, but hey... this is part of what I signed on for. Plus, there's the cash...