I'll answer your question in two parts:
A lot of VCs are generalists. Even the ones that cover specific areas such as Technology are generalists across large focuses (i.e., Healthcare, Software, Infrastructure, etc.). Based on what you said, many of the top tier valley tech VCs will have a general understanding of what you do but your best path to finding the right investors is to find comparable companies (ideally not one that you compete with) and look who their backers are (i.e., BlueKai was backed by e.Ventures, Battery, GGV and Redpoint). Since you mentioned big data, one VC that has a large focus on it is Data Collective.
Second part: For what sorts of investors you should be approaching, I'd think about what your pain points are and what you foresee as the upcoming challenges in the next 3-5 years. From that, I'd narrow down the type of investor you'd want (tech-expertise, S&M and operational experience). There's a lot of "dumb" money being thrown around where people just sit on boards and nothing more - in my opinion, it's worthwhile to take a little discount on valuation for the right investor that can help you achieve your goals faster than standalone.