Hi there,
Personally I am just starting to apply for B-schools this summer, so I do not have the experience. However, I think I can share with you what I have learned from some of my research.
1. GMAT matters:
Let's face it, if it didn't, we would not have this forum to discuss this issue on. Try to get a 720+ on your GMAT, and it will significantly help you overcome the low GPA you had back in school. Every school or even program has their way of measuring the students' academic achievement, which we all know is not the most accurate science out there. GMAT is a fair playing ground for you to demonstrate what you are really capable of. Especially after a few years of working like you mentioned, you're experience and your GMAT are way more important than your undergrad grades. Don't get me wrong, it is awesome for some people coming out of school with 4.0 average, but you consistently (except for one term) have above 3.0 from and Ivy league school, I don't think it is something you have to lose sleep over for.
2. Optional essays:
Most top-tier (top 15) schools have an optional essay for the admission officers to understand you a bit more. Utilize that opportunity to explain your experience back in school, and how you tried to mitigate it afterwards to make them realize you are not a quitter and you just screwed up that one semester.
3. Work and reference:
This is probably the second most, if not the most, important part of the whole application package you will present to your dream schools. Make sure you outline some great achievements you have during your work, and this will help you gain an edge over some other people with great undergrad marks but crappy work experience. Each school, with the exception of HBS, typically asks for two professional references. Try your best to establish a good work relationship with your manager and co-workers so you get good references.
4. Extra-curricular activities:
This one is up for debate, but I would say join some organization for a good cause and actively spend time there. This, in my most humble opinion, will be the tie breakers when you have a bunch of smart applicants with 700+ GMAT scores in front of you.
To summarize, I think you still have a fair chance. I am not saying you're guaranteed a spot at Columbia or MIT, but you should definitely try to gear your education future towards that.
Those are just what I have learned from researching and discussion with people who have gone through the application process, maybe it was all garbage, but maybe some of the things I pointed out will turn out being helpful. Good luck buddy!
stevkang8