Just adding my two cents. We leave next week for our second
Disney cruise. My daughter just turned 6 (today actually!!). We did one last year and absolutely loved it.
I think as a single parent is it a great way to vacation. You can do as much or as little as you would like. The kids clubs are great so make sure to take advantage of some "me" time. I have a spa reservation and both Palo dinner and brunch booked for our trip.
Your girls will have a lot of fun - there is so much to do you cannot possibly do it all. Plus, on a cruise, you are never more than a couple of minutes from your room for a nap or whatever.
I would also suggest (as a PP did) that you join the meets thread for your cruise. We have a great one going for our trip next week. There are about 40 families that have been chatting back and forth on our own facebook page. I know becasue of that group that there are several girls about the same age as mine that she will get to meet right away.
Also, there was another single mom on our meets thread. We decided to link our dining so we can dine together each night. But, last year,
DCL sat us at a table with a family with daughters about the same age as mine. We had a blast all week. I didnt ever feel out of place
Have a great time!!! You wont regret it!