I just wanted to share with you me experiences with open adoption. I know every situation is different as is every birth parent, adoptive parent, and agency. From an agency perspective, open adoption can range from phone calls and letters to in person visits. The agency we used had a more open policy than most, and the average level of connection between birth and adoptive families is 3-5 in person visits per year with letters and possibly phone calls between. Does this sound like the level of contact you are hoping for in a potential family?
I think that you have gotten lots of good opinions here, but please keep in mind how emotional adoption can be for everyone involved. I have experience as an adoptive mother as well as something of an adopted adult, and not as a birth mother so I can't speak from that part of the triad. No one can say if this is the right path for you or your unborn child, but I agree with the PP who suggested you wait until you are further along to make any decisions. If you are curious what sorts of adoptive parents are out there, you can start looking on sites like parent profiles or even local agencies will often have waiting families on their websites.