I hoped there might be some site for making Klingon easy for the guests. Qa pla' To spell it like it sounds. kaa plaa.
Klingon
is spelled like it sounds. It just doesn't sound very much like any other language on the planet, so you aren't going to find a simple yet faithful transcription that the average wedding guest can use without explanation. You can make it very easy, or you can make it sound good. Your choice.
The page Kesvirit linked to is a good guide to making it sound good. There are no pages I know of that make it very easy; that would run counter to a goal of being able to use Klingon for face-to-face communication. If you replace all
H with
kh and all
Q with
kkkh, you might come close. Find a way to describe the half-grunt of a glottal stop and you might come closer.
By the way,
Qapla' doesn't sound like kaa plaa (unless you're an actor on a TV show who hasn't studied Klingon). The first syllable is
Qap and the second is
la'. If you want to express that in a way that the average wedding guest will have a good chance of getting right, try
kkkhap-LA(hic).