Whatever you do, make sure you have insurance that will cover you if you have to cancel for something pregnancy related. Whilst its more than likely everything will be fine and you'll be basking in a mid-pregnancy glo, its possible that things might not be quite so straightforward (and not even for something particularly life-threatening, just something that makes you uncomfortable enough to want/be advised to stay at home) so it would be prudent to make sure you'll not be too out of pocket in that event.
I went to North America when I was about 20 weeks in one pregnancy and had a fantastic time (just made sure I wore flight socks, drank plenty of water and tried not to sit too still for too long). Another time I did 2 weeks in a tent at about 25 weeks and still had a good time (although traipsing across the campsite at 2am every morning to visit the toilet block wasn't quite so fun...)
One thing I did find, though, was that I was less tolerant to heat/humidity than normal. I don't particularly enjoy high temperatures regardless, but I found that once it got above about 26C I would rapidly start to feel quite ill unless I could find a cool, shady spot and sit quietly with a cold drink. You might be absolutely fine and a complete sun-baby, but just be aware that your pregnancy might make you less tolerant of conditions you'd previously have revelled in.
I'd also be cautious of too big a time difference for a 1 week holiday, but that's just me (and having been shipped out to the far east, economy, for a week for work once - think I'd barely got over the jet lag before it was time to come home again!).
Whatever you decide, have a fantastic time :o