Originally Posted by varjag
Unless it'll be extremely hot, a few weeks should not be a problem.
I agree wholeheartedly.
I think a few of the posts here are a little over-cautious. Yes, you should keep the exposed (or unexposed for that matter) film out of extreme heat and direct sunlight - but otherwise it will be fine for several weeks or even months.
I do like the idea of mailers, however, for a different reason - it avoids x-rays if you are flying to your destination and need to go through a security scan. Also, if you time it right - you will be greeted when you get home with developed slides ready for viewing or scanning!