I'm not a vascular tech. Used to do general (abdomen, ob, "small parts" - ie, thyroid, testicle, breast), now I do high-risk fetal. I personally don't much care for vascular; it never grabbed me, so I never really trained in it. Some people absolutely adore it, though.
Sonography is a great career. You just have to be the right person for it. That's why, as njbmd said, you should find out as much as you can and shadow. Shadow techs in several areas, if possible (echo, vascular, ob) and ask them what they like and don't like about their jobs.
What I like: it's interesting. I learn new things every day. I have some autonomy, and that increases as the docs get to trust your clinical judgment. I get to catch ectopics before they rupture, and find subtle fetal anomalies. I have great benefits and a good hourly wage.
What I don't like: the ergonomics factor - work-related MSK injuries, pain, soreness, etc. Limited upward mobility, small 'scope of practice' (if such a phrase can be applied to a tech position). Occupying the weird tech space, where many patients think you know everything and are just withholding it, and some doctors and nurses think you don't know anything. Not much opportunity for further education- there's no master's program yet (to my knowledge), and very few bachelors programs.
There is a lot of flexibility among positions, which is nice. Many positions require a lot of call (which *sucks*, but pays VERY well), but there are a lot of PRN (as-needed) positions where you can have more flexibility. You can work for a hospital or a doc's office, or freelance with a laptop machine and be mobile, if you partner with a radiologist.
Definitely look into it. It's a fast expanding profession. I get recruitment emails and postcards all the time from all over the country, many with sweet sign-on bonuses. Just make sure you can be happy in a subordinate position, where you are not allowed to give patients results, and where you do not have final responsibility for the patient or the outcome. And if you already have carpal tunnel syndrome, tendonitis or back problems you really might want to think twice.