Excerpt length

I have my website pretty much complete and it looks good. The only problem I have now is that because the "excerpt" for the featured slider has to be the same number of words for all of the pages, I either have to A) have some of them end randomly in the middle of a sentence, or B) I have to contort the first sentence of each page to have the exact same number of words as all the other pages. I can usually do B, but then when a visitor clicks on the link, the the first sentence does not really sound right. Is there any way to adjust the excerpt length for each featured slider page? Thanks.