In reply to Red Rover:
I'm a vet, which does allow me a certain freedom.
But within any job, getting a 3-4 week holiday oughtn't to be a massive issue, particularly if you're doing something fairly character building. I sympathise with all those who feel that their chances were lost through kids/mortgages/jobs, but honestly feel that they're talking b*ll*cks (with all due respect). We travelled quite widely from mid-20s to early 30s (with one big trip at the start and then smaller ones as and when funds permitted), then got our heads down and did kids and a mortgage, with the result that we paid off a cheap house a couple of years ago and started to travel again. We have no job security, no pension and no particular plan, but the house is ours and what used to go on the mortgage now goes into a travel fund. We won't be taking any big trips for at least ten years, when the kids are through school, but a month here and there will be happening and there's almost nowhere you can't reach in a month.
If you accept that you don't need a ridonculous house or flash car, travelling's easy to achieve.
Martin