Have a look at post graduate certificates instead of a bachelors degree. I work full time and have just completed a Graduate Certificate in Finance. The benefit of this is that it is only 1 year part time and can lead to a Post Grad Diploma and then Masters in the same time it would take you to get an Undergraduate Degree.
I am certain with your work experience you can get into a Post Grad course, that's what I did (no Undergraduate Degree).
As for if it is useful, absolutely. As others have said it not only helps you in your career but also teaches you to think differently.
100% agree with this.
i work full time and currently doing an MBA (masters of business adminstration). ive bypassed the whole undergraduate thing by going straight to masters (work experience gets you in - i just sent a resume to the uni).
bachelors degrees arent as highliy regarded as masters and i believe masters are more focussed and relevant as opposed to some of the waffle and fluff they bore you with in undergrad..