Why not enjoy this trip with your family and kids? . . . but that doesn't mean having alcohol, you don't need alcohol to enjoy yourself, it is not the centre of the social universe!!
The reward after 3 weeks is going to mean throwing 3 weeks away, so is that really a reward? I think re examining your reasons to be Sober is a good idea, as if a reward is required every now and again is this not going to be a never ending circle, a merry-go-round I was on for years.
For me Sobriety had to be all or nothing, and that didn't mean any less enjoyment, any less fun, I simply had to readjust my lens to realise enjoyment can be had without alcohol, and spending time with your family shouldn't be conditional on having alcohol.
Are you going drinking or going to enjoy time with your family? I'd focus on the latter!!