If you can get a weekend away, you can use it to restore your energy and to just have some time for yourself. Try one of these options:
Spas were created for one reason -- to help you relax. Go with friends or go by yourself, but you can likely find a spa within driving distance where you can spend the weekend getting massages, facials, taking nature walks or just relaxing with a book.
You can also look for getaways that are theme or activity oriented. If you like wine, find a vineyard that provides weekend classes and excursions. If you want to focus inward, you can find any number of meditation, spirituality or self-discovery types of retreats. Or you might decide to find a weekend package that focuses on developing a skill -- anything from leadership to kayaking.
If you do find yourself with a free weekend, you might decide that the best way to spend it is with your partner -- out of the house. Whether you visit someplace new or just stay in a local bed and breakfast, you can find a romantic getaway for just the two of you. If you are feeling budget conscious, then kick the kids out of the house for the weekend (perhaps they can stay with the grandparents or with friends) and the two of you can enjoy the quiet of your own home.
One of the best ways to find time for yourself is to take chores off your plate. If you aren't going to go away for the weekend, at least don't spend it cleaning. Hire a cleaning service (make sure it's bonded and insured) to take over. If you can't do this regularly, you can make it a treat for yourself on occasion.