Punctuation Inside ( ) While Ending a Sentence

Looks fine to me, although "Have fun in your meeting (or don't have fun at all)!" would make just as much sense, and probably wouldn't look as awkward to you.

I like Dave's suggestion.

It's correct to have punctiation at the end of a sentence. It does look awkward having a bracket followed by a full stop, but then, if you want to apply an exclamation to the remark in parenthesis, you'll have to write it that way.

Alternatively:

Have fun in your meeting - or don't have fun at all! might work too.

Colin

Yup, it's fine. Don't worry.

I was reading the translation of Wim Wenders' The Act of Seeing and there the translator had a footnote that ended thus: ...(Trans.).
I guess that publishers use different system of punctuation. The above-mentioned book is Faber&Faber's and their stuff is very different that, say, Routledge.
However the same subject's been also discussed at:
http://www.painintheenglish.com/post.asp?id=180

The period at the end of TRANS doesn't signify the end of a sentence, but rather an abbreviation, so it's not really comparable.

You don't need the period, that's all.

If you don't use the period, you should put the exclamation outside the parentheses. The phrase inside the parentheses is not a sentence (It is a continuation of the sentence.), and does not need its own period or exclamation.

Have fun in your meeting (or don't have fun at all)!
or
Have fun in your meeting. (Maybe you won't have fun at all!)

I think the way you wrote it is just fine.