I am in the Plano area as well. I have regular sitters (16-19yrs old) come at least one night a weekend for date night. I guarantee $60 for the night (usually 7:30 until about midnight, sometimes a little later). I have one 12yr old. If I have to cancel my sitter the day before up until time for her to show, I pay her $40 because she held the night for us and does not deserve to be shortchanged if we have a change of plans. 12 yr old sleepovers, sickness, etc.
When I tag along on travel with hubby for short trips, I pay $150/24hrs plus any other expenses such as transportation, food, activities. We also have pets and she helps take care of them as well. The overnights are covered by a college student who has been sitting for us for about 3 yrs.
Hope that helps.