Good choices mae. Of past themes I liked the songs of the 50's and when they had songs from Bon Jovi the most. My themes would include those but would like to add the following:
Songs of the 80's
INXS music
Motown would be okay but not their usual songs they sing from that era, maybe they could pick a particular artist like Smokey Robinson or Marvin Gaye
Country night would be okay if they picked music from people like Willie Nelson, Johnny Cash, Tammy Wynette, Conway Twitty or Loretta Lynn, etc. I like the old country music, can you tell?
On season 5 finale they had the group sing songs from Burt Bacharach which would be another theme they could do
I doubt they could sing an original song as many of these contestants do not write their own music so instead I would like them to sing a song from their favorite artist
How about the music of Linda Ronstadt, Cher, Madonna or Cyndi Lauper. Each of these women do have songs that would fit a guy or a girl
The music of Barry Manilow who has had tons of hits. Tom Jones or Van Morrison is another consideration
:) I could go on and on about different artists. I just hope they do something different this time as I have kind of tired of the usual stuff our contestants have to choose from.