Yay! That is the perfect time to take a vacation! I went to The Big Island when I was about 22 weeks with DD1. It was great. I was a little more careful when we went hiking and there are some activities we normally do that I couldn't (like ATVs, etc.) but it honestly made the vacation a little more relaxing.
I started to have a potbelly around 20 weeks, but I think most people thought I just had a big lunch. No big. Just rest your hand on your tummy and people know exactly why you look like you nom-nomed a monster burrito.