I feel sad that your mother won't help you, but if your husband has enough vacation and is willing to use it, I say go. Your husband better than anyone knows that you are a good Mom and it sounds like he thinks you need or deserve a break.
EDIT: SORRY THIS IS LONG, I HAVE STRONG THOUGHTS ON THIS.
I am again reminded of how lucky I am. My parents always believed that people need different types of vacations. There is family time, couple time and personal time and we all need a blend. I had grandparents who agreed and loved to be with us (I assume that they did since they kept coming back!). I am one of 4 kids within 6 years of age so my mommy was very busy. She was (still is) a great mom, and i think that some balance is why she was so good. I had one set of grandparents who lived close bye, they had some or all of us at least once a week. My grandfather would come get us for a few hours and just take us on errands (the bank, stores, etc.). My grandmother would keep us overnite some weekends. It was a treat when it was my turn.
We always took a family vacation in the summer to visit my other grandparents who lived about 5 hours away. They lived in a mountain area and had a boat, so we would go to lakes and picinic and boat. Sometimes we would camp for a few days. These were "cheap" and great fun family times. Then about once a year there was some sort of other trip. They seemed to alternate. Some years my folks would go away and my grandparents would drive down and stay for the week. These trips were as much fun for us as my parents. We loved being spoiled for the week. Other times we would go away as a family (Disney of course, Williamsburg, Canada, New England, the beach etc.). When I got a little older, my parents added individual trips to the mix, Dad would golf with friends, Mom would visit her sister, etc. We particularly loved when Mom went away because my Dad never followed her "instructions". We would go out to eat, stay up a bit too late, etc.
Now that we are all grown and have our own kids, my mother babysits someone at least 3 or 4 times a week. She answers the phone at 6 am when my SIL or I call and say "my kid is too sick to go to daycare", she watches my sisters kids so she can work one day a week, she will take my DS on a Saturday for that wedding we are going to and tell us not to worry about coming back- just get him tommorrow, and she watches our kids so we can go on vacation. My husband and I went to Hawaii, my Brother and SIL went to the Bahamas, my sister is going to florida.
