My friend and I are having these same emotions, so it's normal. In my case, I will be tagging along with my husband on a business trip to Orlando. While he's in meetings all day, I'll be heading to Disney all.by.myself. We're also tacking on a few extra days to spend at Universal to see the Wizarding World of Harry Potter -- a double-whammy guilt trip.
I feel really, really guilty leaving them behind because I know how much fun they would have and feels so selfish to cut them out of that equation. That's what I struggle with the most. I have lots of friends and family who do leave their kids behind, and I asked them (via facebook) how they do it. A lot of the responses were similar to the ones here.
At the end of the day it boiled down to a few things:
1. The kids need to see you and your husband do fun things together and spend quality time together.
2. When I was a kid, I remember reading in a newspaper: The best thing a kid can hear their parents say is, "Your mom and I are going on vacation!" When I was younger, I loved it when my parents left town. Sure I missed them, but they brought back fun things, and we could relax a little bit. We always had fun babysitters and got to stay up late watching movies.
3. With technology it is so much easier to keep in contact with them if you do miss them so much or feel guilty. I plan on taking lots of pictures in the souvenir stores, texting them, and shopping together via the iPhone. You can facetime in the park, video the parade and send it right away, or call as often as you need. Nowadays we really are just a call or click away.
4. Finally, someone commented to my friend who is feeling the same that you were a wife/girlfriend before you were a mother, and that relationship needs to be nurtured as well. Your husband deserves some one-on-one time with you too. He needs his wife, best friend, and yes, lover just as much as your kids need their mom. 10 years of putting up with each other and making a marriage work is worth celebrating, and you TWO were the ones who did that. Enjoy that!
There were more thoughts, but those are the ones most prominent in my mind at the moment. I know from first hand experience how agonizing it is, and I've only done it one other time when my husband and I went to Hawaii several years ago. To help with that, I left a prize for every day we were going to be gone for our daughter. It gave her something to look forward to, reminded her that we loved and were thinking of her, and acted as a countdown to when we'd be back.
Good luck and have fun planning your trip. It's a win-win all around.