Uniques monthly is totally meaningless.
This comes up with some frequency. Uniques daily * 30 != uniques monthly, after all, if you undouble on a monthly basis and you get 30K visitors each day and they're all different it looks like you have a cool 900K uniques monthly. But at the same time it means you are completely not sticky! All your users are replaced by new ones every single day.
A better measure is uniques daily, daily growth in uniques and compare that with your uniques monthly. If you're doing it right you should see (30average repeats) + (30average growth)
Those are figures that you can do some planning on. Monthly uniques does not do anything other than look good on paper. Bad websites look even better :)