No problem. Send me a PM a little closer to the convention and we can try to work out some details.
Keep in mind that the pool is a key-locked enclosure, so for a proposal, you'll need to keep it tight. You, me, your fiance, and maybe someone to take a video for you unless you want me to do it.
After that, we can pick a date and we'll figure out timing since I'll have some responsibilities I can't skip, but if we can do it closer to the afternoon sun/sundown, it should be an good view. That, or at night with L.A. Live hopping and the light of the Convention Center in the distance.
Your call. =)