This is one of the quintessential camp songs of all time, and I think everyone who has EVER attended camp remembers this song in some form or another. In the many years I attended YMCA Camp Tippecanoe in Ohio (which I HIGHLY recommend if you are considering sending your child to a summer camp) I heard 3 different versions of this song. They generally follow a pattern of either being sung fast or slow, but I've heard all three both ways (slow is much better IMHO.)

Anyways, Here are the versions... I break them down by the sound you make between lines, but the lyrics are actually different and if you attended camp your version could potentially be different yet, however, I'm willing to wager it is very close to one of these three.

Version #1

Generally in this version they broke the singers into two groups, one group would do the Mmm-Hmm's and the other group would do the actual lyrics, it was quite nice, and this is the version I heard the most and consider 'classic'. Usually this was a quite slow version.

Chorus:
(Mmm-Hmm) I'd like to linger
(Mmm-Hmm) A little longer
(Mmm-Hmm) A little longer with you

(Mmm-Hmm) It's such a perfect night
(Mmm-Hmm) The stars are shining bright
(Mmm-Hmm) This is my very last with you

Chorus

(Mmm-Hmm) When it comes September
(Mmm-Hmm) We will remember
(Mmm-Hmm) Our camping days gone and through

Chorus

(Mmm-Hmm) As the years roll by
(Mmm-Hmm) I'll think of you and sigh
(Mmm-Hmm) This is good luck and not goodbye

Chorus

Version #2

I have only heard this version twice, both times in the same week, it was sung pretty rapidly and I missed an entire verse in memory (had to do some searching to find it.) The lyrics are smoother in places in this version when compared to the 'classic' version I suspect this may have been very very similar to the original version... it seems to make more sense lyrically.
Chorus:
(Ah-Oh) I'd like to linger
(Ah-Oh) A little longer
(Ah-Oh) I'd like to stay right here with you

(Ah-Oh) It's such a starry night
(Ah-Oh) It doesn't seem quite right
(Ah-Oh) That it should be my last with you

(Ah-Oh) And come September
(Ah-Oh) We will remember
(Ah-Oh) Our camping days and friendships true

(Ah-Oh) And as the years go by
(Ah-Oh) We will remember why
(Ah-Oh) We said goodnight and not goodbye

Chorus

Version #3

I don't personally care for this version, the Oo-Ooh doesn't flow as well as Mmm-Hmm and the lyrics don't flow nearly as well as the second version either, I suspect this is a bastardisation by someone who couldn't remember the correct lyrics any longer.

(Oo-Ooh) I want to linger
(Oo-Ooh) A little longer
(Oo-Ooh) A little longer here with you

(Oo-Ooh) It's such a perfect night
(Oo-Ooh) It doesn't seem quite right
(Oo-Ooh) That this should be my last with you

(Oo-Ooh) And come September
(Oo-Ooh) I will remember
(Oo-Ooh) Our camping days and friendships true

(Oo-Ooh) And as the years go by
(Oo-Ooh) I'll think of you and sigh
(Oo-Ooh) This is good-night and not good-bye

'ware thee o'singing this song mortals! For if thou choose so silly a fate it shalt haunt thine mind for the rest of thine days!*

* In other words, its one of those evil songs that sticks in your head... FOREVER. Right up there with The Bear Song and Froggy. Fear.