check out the hilltops. go and recce and see if you have a clear view of the east from various hill parks such as Fort Canning and Telok Blangah Hill. Remember it will be dark when you go in on the actual day. I am assuming you are going to bring your love interest, so make sure she is up to it in terms of darkness, desertedness and insects
This I must agree... long time back I was fortunate enough to be invited into a cockpit of a 747B, the one with upper deck for business class passengers. Witnessed sunrise from the cockpit in one of my flights to US, this was of course before all the strict security procedures lah.
Sat on the left side behind the pilot and saw an amazing sunrise, it was quick though. I think sunset would be longer depending on which way you are flying (to US or to SIN)
Now I don't think they will entertain any such request.