You ask a good question, but there are three or four things you need to consider as well:
1) Getting recruited is directly related to how many college coaches know you, know OF you, and/or have seen you play. Some college coaches are fine with video, others are more "old school" and need to see you in person to pass judgement.
2) Which coaches and which schools you contact is, to a large degree, a guessing game as to whether or not you would be considered a good or hot prospective recruit. Even by looking at their current roster you're not sure what they need or WANT in their recruiting class, so limiting yourself to a region, a class of colleges or a specific Division could be limiting. and;
3) The only way, and I emphasize ONLY way, to talk with coaches is from the athlete to the coach. College is NOT traveling ball or high school where parents are still an active and accepted participant in your sport. Once you're in college you're considered an adult and the decisions made are made by YOU. Your parents are going to be involved in your college financing and, obviously, in helping you choose, but the coaches want to hear from YOU and they want to know YOU as an athlete and a future "coachable" player. They don't get that if your parents write them.
The best way to ensure you're recruited, from DI-DIII is to either accumulate all the information on every school that sponsors baseball and then contact each coach individually yourself, or use a site that's designed to do that with and for you. We've had twelve or thirteen of our area kids use RecruitU2.com for this. The help you build your profile, upload video, create an intro letter and then send your profile, video and letter to every coach at every school where you can get in academically. They only charge one fee and you can update coaches for up to two years for that one fee.
You don't have to use RecruitU2.com, you can do it all yourself. Go to NCAA.org and download the list of schools that sponsor baseball, go to each web site and accumulate information, create a mailing list, create a profile, save your videos on your computer and then look up the academic requirements to get in. Once you have all this info, send out hundreds of profiles.
Remember, exposure is the key. You want every coach to know you're available and either come scout you or invite you to a camp or tournament. That only happens if they know you exist.