My first m/c was very early on and the doctors wanted to let it happen naturally. After about 7-10 days, my hcg levels weren't dropping so they opted for a D&C. The procedure was quick and pretty painless. The second time I m/c'd, I was almost 12 weeks and there wasn't much discussion. The doctor had me get a D&C the next day. But, that's what I would have wanted anyway.
There are a few factors that you can consider before you make your choice. Personally, if the pregnancy was over - I wanted it totally over. I didn't want to wait and wait. I was angry at my body (I was angry at the whole world, actually) and I didn't like not knowing that the baby was still (possibly) in me. But, that was me.
Another thing is that I wasn't on fertility and my age wasn't as much of a factor (I was 31-32). After the D&C, I bled for about a week (?) and was cramping pretty bad. We were told to wait for two cycles and then we could start again. We were blessed because I get pregnant VERY easy. I've been pregnant four times and 3 happened the first cycle and the 4th was the second cycle of trying.
As for the D&C and future fertility... I do seem to remember that there was some increased risks for the future and pre-term labor or something. I'm not sure though. Please check with your doctor or WebMD or some other reliable website.
Finally, I should warn you that IF this ends up being the route you need to take (I'm hoping not), you may have the word "abortion" or "spontaneous abortion" on paperwork or used by medical professionals. This really threw me for a curve as I was sad to hear/see those words with regard to my situation. I'm pro-choice, but it was upsetting to me. One of the nurses at my doctor's office was kind enough to apologize for the fact that the paperwork even had it on there. ALSO, when I was at the hospital for the procedure, I had to sign a release that would let them take "the products of conception" and that I didn't want "it" for any religous purposes. THAT really hurt for some reason and made the whole thing just so real. I started to cry when I had to sign the paperwork. So, just be prepared.
I hope that all turns out ok for you and your baby. I'll keep you in my thoughts. Please let us know.