Hi
Firstly i am terribly sorry to hear about your loss, thats very sad indeed. I think its a lovely thing that you are doing and wish you luck in getting the right pictures.
I think its tricky as close up you will benefit from a flash but as they get further away i would be looking to get as much natural light as possible so i agree that twilight would be best, i think it would make for a better natural shot as you will have horizon light contrasting with rich lantern paper colours and the candles below. Also had you thought of getting a long exposure shot in bulb mode. It would make a stunning shot of the lights going upwards in their own light trail.
See the following links for my idea of good pics for inspiration:
http://www.dailymail.co.uk/news/arti...ight-year.html
This i like for the perspective underneath:
http://www.guardian.co.uk/travel/gal...02/photography
Check 4th pic down:
http://pixdaus.com/index.php?pageno=...tival&sort=tag
And i love this, such a great photo:
http://holykaw.alltop.com/a-midsumme...r-poland-video
And finally:
http://www.telegraph.co.uk/earth/agr...-lanterns.html